Limestone Resources of Tanzania: A Comprehensive Geological and Economic Review

May 31, 2025

KILIMOKWANZA.ORG TEAM

I. Introduction

A. Overview of Limestone: Definition, Composition, and General Economic Importance

Limestone is a sedimentary rock primarily composed of calcium carbonate (CaCO3), predominantly in the mineral forms of calcite or aragonite. While these carbonate minerals form the bulk of the rock, limestone typically contains varying amounts of impurities. These can include siliciclastic components such as quartz and clay minerals, other carbonate minerals like dolomite (CaMg(CO3)2) and siderite (FeCO3), as well as iron sulfides (e.g., pyrite), chert nodules, and organic matter. The color of limestone is commonly white to gray, but can range to black if rich in organic matter, or exhibit yellow to red hues due to traces of iron or manganese.

The economic importance of limestone is extensive and multifaceted, underpinning numerous global industries. It is an indispensable raw material in the manufacture of cement, where it serves as the primary source of calcium oxide. Furthermore, limestone is widely used as a construction aggregate for roads and buildings, and in agriculture as a soil conditioner to neutralize acidity and improve soil structure. Other significant applications include its use as a flux in steel production, in the chemical industry for lime production, in water purification processes, and as a filler in various products such as paper, plastics, and paints. The global limestone market is substantial and continues to expand, largely driven by ongoing construction activities and infrastructure development, particularly in emerging economies.

B. Geological Significance of Limestone in Tanzania’s Mineral Landscape

Tanzania is endowed with a rich and diverse array of mineral resources, encompassing metallic ores, gemstones, energy minerals, and a variety of industrial minerals, among which limestone holds a prominent position. Limestone deposits are widely distributed across the Tanzanian mainland and the Zanzibar archipelago, occurring in a range of geological settings that reflect the nation’s complex and protracted geological evolution, from the Precambrian to the Recent.

Beyond their economic utility, Tanzanian limestone deposits possess considerable geological significance. As sedimentary rocks, many limestone formations serve as valuable archives of Earth’s history, preserving fossils and geochemical signatures that provide insights into past environmental conditions, including marine and terrestrial ecosystems, paleoclimates, sea-level fluctuations, and tectonic events. The study of these deposits contributes to a deeper understanding of the paleogeography and geological development of the East African region.

C. Broad Geological Settings for Limestone Formation in Tanzania

Limestone occurrences in Tanzania can be broadly categorized based on their geological settings, each imparting distinct characteristics to the deposits:

Coastal Basins: These basins, extending along Tanzania’s Indian Ocean coastline, are dominated by marine sedimentary limestones. These deposits range in age from the Mesozoic Era (Jurassic and Cretaceous periods) to the Cenozoic Era (Tertiary and Quaternary periods) and were formed during extensive periods of marine transgression that inundated the continental margin. These limestones are of particular importance for the cement industry.
Karoo Supergroup: This extensive sequence of predominantly terrestrial sedimentary rocks, deposited from the Late Carboniferous to the Early Jurassic, also contains periodic limestone deposits. These are often interpreted as lacustrine or palustrine (swamp-related) in origin, formed within freshwater bodies in the Karoo rift valleys.
Precambrian Metamorphic Terrains: Ancient geological provinces, such as the Mozambique Belt and the Usagaran System, host crystalline limestones, more commonly known as marbles. These rocks are the result of metamorphism of older carbonate sediments and are often characterized by high purity.
East African Rift System (EARS): The Cenozoic development of the EARS in Tanzania has been associated with the formation of carbonatite intrusions, which are igneous rocks rich in carbonate minerals, and related limestone or marble occurrences. Additionally, travertine deposits, formed by the precipitation of calcium carbonate from geothermal hot springs linked to rift activity, are found in this setting.

The varied geological environments in which Tanzanian limestones are found give rise to a wide spectrum of limestone types, qualities, and potential impurities. This diversity directly influences their suitability for different industrial applications. For instance, the extensive marine limestones of the coastal basins are typically well-suited for bulk applications such as cement manufacturing. In contrast, the metamorphic marbles found in Precambrian terrains can exhibit high purity and desirable aesthetic qualities, making them suitable for dimension stone or specialized industrial uses requiring high-grade calcium carbonate. Limestones associated with the East African Rift System, such as carbonatites and travertines, may possess unique geochemical signatures or physical properties. Karoo limestones, having formed in terrestrial or lacustrine settings, are likely to differ in their characteristics (e.g., fossil content, associated impurities) from their marine counterparts. This geological diversity represents a significant national asset but also underscores the necessity for careful geological assessment and material characterization to ensure optimal resource utilization.

Furthermore, the distribution and specific types of limestone in Tanzania are intrinsically linked to the country’s major tectonic and geological evolutionary stages. The formation of crystalline marbles is tied to Precambrian orogenic events, such as the Pan-African orogeny that formed the Mozambique Belt, which metamorphosed pre-existing carbonate sediments. The subsequent breakup of the Gondwana supercontinent, initiated by Karoo rifting, led to the development of extensive sedimentary basins, both along the coast and in the interior. These basins became the sites for the deposition of Karoo-age limestones and, later, the thick sequences of Mesozoic and Cenozoic marine limestones that characterize the coastal belt. More recently, the Cenozoic activity of the East African Rift System created pathways for carbonatitic magmatism and established geothermal systems conducive to the formation of travertine deposits. Consequently, a thorough understanding of this overarching tectonic framework is fundamental for developing predictive exploration strategies for limestone resources across the country, as exploration approaches must be tailored to these distinct tectono-geological domains.

II. Principal Limestone-Bearing Geological Provinces and Formations in Tanzania

Tanzania’s limestone resources are hosted within several major geological provinces and specific rock formations, each with a distinct history of deposition or formation. These range from ancient metamorphosed carbonates to relatively young sedimentary and volcanic-related deposits.

A. Coastal Belt Sedimentary Successions (Mesozoic-Cenozoic)

1. Geological History: Marine Transgressions and Carbonate Deposition The geological history of Tanzania’s coastal belt is dominated by the effects of the fragmentation of the Gondwana supercontinent, which commenced in the Mesozoic Era. This breakup led to the opening of the Indian Ocean and resulted in a series of prolonged marine transgressions that inundated the newly formed continental margin of present-day Tanzania. These marine incursions began significantly in the Middle Jurassic and persisted, with fluctuations, through the Cretaceous and much of the Cenozoic Era. These transgressions established extensive shallow marine shelf environments, which were highly conducive to the widespread deposition of carbonate sediments. The resulting rock record includes thick sequences of oolitic limestones, coralliferous (coral-bearing) limestones, bioclastic limestones, marls, and associated shales.

The development of these coastal sedimentary basins was also influenced by regional tectonic activity. Major fault systems, such as the NNE-SSW trending Tanga Fault and the NNW-SSE trending Lindi Fault, played a crucial role in defining sub-basins (e.g., the Selous-Ruvu-Tanga rift and the Ruvuma-Mandawa basin) and controlling sediment distribution and thickness.

2. Key Limestone Formations

Several key limestone-bearing formations have been identified within the coastal belt:

a. Tanga Limestone (Middle Jurassic – Bathonian): This formation, prominently exposed in the Tanga Region, is primarily composed of limestone and has been dated to the Bathonian stage of the Middle Jurassic, approximately 168 to 166 million years ago (Ma). Well-known occurrences are found at Pongwe and Amboni, which serve as important sources of raw material for cement production. The Tanga Limestone contains characteristic Middle Jurassic coral fossils, including species of Calamophyllia and Microphyllia. The economic significance of this formation is underscored by its utilization by Tanga Cement. Geological studies in the Tanga Basin also indicate the presence of dolomitic limestones, which have been considered as potential hydrocarbon source rocks.
b. Kidugalo Formation (Middle Jurassic – Aalenian to Bajocian): Located within the Ruvu-Tanga sub-basin, the Kidugalo Formation is another important Middle Jurassic carbonate unit. It exhibits internal lithological variation: the lower part of the formation, sometimes referred to as the Kidugalo Oolite, comprises silty calcareous sandstones and oolitic limestones. The upper part, particularly in the vicinity of the Kidugalo railway station, is characterized by an ammonite-rich marl and shale sequence. The presence of ammonite species such as Planammatoceras has confirmed an Aalenian age for portions of this formation. Stratigraphically, the accumulation of the Kidugalo Formation, along with the Mtumbei Formation, marks the post-rift phase of basin development that commenced in the Middle Jurassic with a significant marine transgression.
c. Lugoba Formation (Middle Jurassic – Bajocian): The Lugoba Formation consists of coralliferous limestones that form a series of small, isolated hills trending NE-SW in the hinterland of Dar es Salaam. These outcrops extend from the Wami River area southwards through Msata to Lugoba. This formation unconformably overlies the Precambrian metamorphic rocks of the Usagaran Belt and appears to transgress across the Tanga Fault system to the west. Lithologically, the Lugoba Formation shares similarities with, and has been correlated to, the Kambe Limestone series found across the border in Kenya. The fossil assemblage, particularly ammonites such as Dorsetensia and Oecotraustes, indicates a Lower Bajocian age for these deposits. Associated fauna include pelecypods, gastropods (e.g., Nerinea), and corals. A typical stratigraphic profile at Msata reveals basal conglomeratic sandstones, overlain by pebbly coralliferous limestones interbedded with fossiliferous sandstones, and capped by hard, bluish-grey, fossiliferous silty limestones.
d. Mtumbei Formation (Middle Jurassic – Bajocian-Bathonian): The Mtumbei Formation was also deposited during the widespread Middle Jurassic marine transgression, coevally with parts of the Kidugalo Formation. It is recognized in the Mandawa Basin in southeastern Tanzania. While detailed studies on the Mtumbei Formation itself often focus on associated thick black shales that have been investigated for their hydrocarbon source rock potential , the formation is explicitly cited as a limestone unit within the regional stratigraphy.
e. Tertiary Reef Limestones (e.g., Wazo Hill): Younger limestone deposits of Cenozoic age are also significant, particularly the fossil reef limestones of the Tertiary era. A prime example is Wazo Hill, located near Dar es Salaam. This prominent topographic feature is composed of Tertiary fossil reef limestone and represents one of the largest carbonate occurrences along the Tanzanian coast, holding substantial limestone reserves. It is actively quarried for cement production by the Tanzania Portland Cement Company (TPCC). The chemical composition of the Wazo Hill limestone is reported to be mainly CaCO3 and SiO2.
f. Other Cenozoic and Quaternary Limestones (including coral limestones of Zanzibar): Recent geological surveys conducted by the Geological Survey of Tanzania (GST) have revealed the presence of high-quality limestone suitable for cement production in the Zanzibar archipelago. The historic Stone Town of Zanzibar is famously constructed using local coral stones, which are predominantly composed of aragonite (a polymorph of CaCO3) and have a high CaO content; these are currently the subject of material degradation studies. Furthermore, modern carbonate sediment accumulations are found, for instance, on the east coast of Zanzibar (e.g., Chwaka Bay, Pongwe), where sediments comprise almost 100% biogenic calcium carbonate. In a broader context, coastal sedimentary aquifers within these Cenozoic and Quaternary sequences generally exhibit better groundwater productivity from limestone and sandstone horizons compared to interbedded shales and marls.

The Jurassic period, especially the Middle Jurassic, emerges as a particularly critical epoch for the genesis of economically important limestone deposits within Tanzania’s coastal belt. This is evidenced by the dating of multiple key formations—Tanga Limestone, Kidugalo Formation, Lugoba Formation, and Mtumbei Formation—to this timeframe. This period of extensive carbonate deposition coincided with major marine transgressions that followed the initial rifting stages of Gondwana and the opening of the Somali Basin. The resultant widespread shallow marine conditions provided ideal environments for the development of carbonate platforms and prolific reef growth.

The specific quality and type of limestone found in the coastal belt—such as oolitic, coralline, and reefal varieties—are directly attributable to the particular depositional environments that prevailed. These environments were shaped by a complex interplay of eustatic sea-level changes and the tectonic behavior (stability or subsidence) of the evolving passive continental margin. Oolitic limestones, for example, as seen in parts of the Kidugalo Formation , typically form in shallow, high-energy marine settings with strong currents. Coralliferous and reef limestones, characteristic of the Lugoba Formation , the Tertiary deposits at Wazo Hill , and parts of Zanzibar , require clear, warm, shallow marine waters conducive to coral proliferation. Such conditions were widespread during the Mesozoic-Cenozoic marine transgressions. A key consequence of these depositional settings is that the resulting limestones are often of a purity suitable for cement manufacture (i.e., high CaCO3 content), primarily because these environments tend to minimize the influx of terrigenous clastic material from land.

B. Karoo Supergroup (Late Carboniferous – Early Jurassic)

1. Characteristics of Limestone Occurrences The Karoo Supergroup in Tanzania is a thick and extensive sequence of predominantly terrestrial sedimentary rocks, including sandstones, shales, conglomerates, and mudstones, which were deposited in rift valleys that formed during the initial stages of Gondwana’s fragmentation. While clastic sediments dominate the Karoo, geological literature notes the occurrence of “periodically, limestone deposits” within these successions.

More specific details emerge from studies of the Karoo sequence in the Tanga Basin, where the depositional history began with conglomerates and sandstones, followed upwards by turbidites that alternate with “occasional thin limestone layers”. Given the overall terrestrial to marginal marine setting of the Karoo, these limestones are generally interpreted as being lacustrine (lake-formed) or palustrine (swamp- or marsh-formed) in origin. They likely precipitated in freshwater bodies that periodically developed within the extensive, predominantly terrestrial Karoo landscape.

Limestones within the Karoo Supergroup are volumetrically minor when compared to the extensive marine limestone formations of the coastal belt. Their non-marine origin suggests that they are likely to possess different chemical and physical properties. The depositional environments for Karoo sediments were overwhelmingly terrestrial, dominated by fluvial and lacustrine systems. Limestones forming in such settings—freshwater lakes or swamps—typically differ from their marine counterparts in terms of fossil content (often non-marine or restricted fauna and flora), lateral extent (can be more localized), and potentially purity. They may, for example, contain a higher proportion of silica or clay derived from contemporaneous terrestrial runoff from the surrounding highlands into the depositional basins. The description of “thin limestone layers” within the Karoo sequence in the Tanga Basin further supports the interpretation of these deposits being of limited thickness and extent relative to the major marine carbonate units.

C. Precambrian Metamorphic Terrains (e.g., Mozambique Belt, Usagaran System)

1. Formation of Crystalline Limestones and Marbles Tanzania’s ancient Precambrian geological framework includes extensive metamorphic terrains that also host significant carbonate deposits, albeit in a metamorphosed form known as crystalline limestone or marble. The Mozambique Belt, a major Neoproterozoic orogenic belt that abuts the eastern margin of the Tanzania Craton, was formed during the widespread Pan-African orogeny. This belt is composed primarily of highly metamorphosed rocks such as gneisses and schists, but it also contains “smaller occurrences of graphitic schist, quartzites and crystalline limestone”. Similarly, the Proterozoic Usagaran System, another significant metamorphic complex in Tanzania, is known to host crystalline limestones.

These crystalline limestones are the result of regional or contact metamorphism of pre-existing carbonate sedimentary rocks (limestones or dolostones). The intense heat and pressure associated with metamorphic processes cause recrystallization of the original carbonate minerals, leading to the characteristic crystalline texture of marble. The Morogoro Region is particularly noted for its “white marble deposit,” which is described as being of high purity.

The Precambrian crystalline limestones (marbles) found in Tanzania, especially the well-documented deposits in the Morogoro Region, represent a distinct category of limestone resource. Their primary suitability lies in applications such as dimension stone, owing to their often attractive appearance and durability, and potentially for high-purity industrial uses where chemical composition is critical. This contrasts significantly with the sedimentary limestones of the coastal belt, which are primarily exploited for cement manufacturing. The process of metamorphism not only recrystallizes the carbonate minerals but can also lead to purification by driving off volatile components and remobilizing certain impurities. The specific description of the Morogoro deposits as “white marble deposit of high purity” strongly suggests their appropriateness for applications where color (whiteness) and high chemical purity (high CaCO3 content, low impurities) are paramount. Such applications include high-quality dimension stone, chemical-grade lime, fillers for paints and plastics, and potentially in the paper or pharmaceutical industries. Their geological setting within ancient, highly deformed and metamorphosed terrains is fundamentally different from that of the younger, unmetamorphosed sedimentary limestone sequences found in the coastal basins.

D. East African Rift System (EARS) Associated Deposits

The East African Rift System, a major Cenozoic geological feature, has also given rise to specific types of limestone deposits in Tanzania, primarily through volcanic and geothermal processes.

1. Carbonatites and Associated Limestone/Marble: Carbonatites are unique igneous rocks predominantly composed of carbonate minerals (typically calcite and/or dolomite). In Tanzania, carbonatite volcanoes began erupting during the Cretaceous period, with activity continuing into the Cenozoic, often in spatial association with the rift valleys of the EARS. While often explored for associated economic minerals (such as phosphates, rare earth elements, niobium, fluorite), the carbonate matrix of these intrusions can itself constitute a limestone or dolomite resource. The Mbeya Carbonatite, also known as Panda Hill, is a notable example; although primarily investigated for its pyrochlore (a niobium mineral) content, it is inherently a carbonate-rich igneous body. The Songwe Scarp carbonatite, also in the Mbeya region, is associated with significant phosphate occurrences and also contains limestone, partly in the form of travertine.
2. Travertine Deposits: Travertine is a form of freshwater limestone that is deposited from calcium carbonate-saturated waters, typically around mineral springs, especially hot springs. The geothermal activity associated with the EARS provides favorable conditions for the formation of such springs. In the Mbeya Region, calcareous sedimentary rocks, identified mainly as travertine, occur in the Songwe valley. These deposits are actively mined for various purposes, including dimension stones, for calcination to produce lime, and as a raw material for cement production. These travertine deposits are reported to cover a significant area of approximately 13 square kilometers and can reach thicknesses ranging from 5 to 70 meters. Furthermore, recent surveys by the Geological Survey of Tanzania in regions such as Arusha, Manyara, Dodoma, Singida, and Shinyanga have identified numerous hot springs. While these are being explored for geothermal potential, they also indicate areas where travertine deposition may have occurred or could be ongoing.

Limestone resources associated with the East African Rift System, namely carbonatites and travertines, represent localized but potentially high-value or geochemically distinct carbonate sources. These differ significantly from the extensive sedimentary limestone provinces of the coastal belt or the regionally metamorphosed marbles of the Precambrian terrains. Their mode of origin—magmatic for carbonatites and hydrothermal or spring-related for travertines—implies different exploration targeting methodologies and potentially different suites of associated co-products or impurities. Carbonatites, being of igneous origin , often have economic interest focused on minerals like pyrochlore, rare earth elements, or phosphates that are concentrated during the magmatic process. However, the carbonate minerals forming the bulk of the rock can themselves be a source of limestone or dolomite. Travertines, on the other hand, form relatively rapidly at or near the Earth’s surface from the precipitation of dissolved minerals from geothermal waters. This mode of formation can result in unique textures and, in some cases, high purity, making them particularly suitable for applications like dimension stone or for producing specialized lime products. The EARS provides the essential tectonic, magmatic, and geothermal framework necessary for the genesis of both these types of carbonate deposits. This contrasts sharply with the slow, widespread depositional processes characteristic of marine limestones or the regional metamorphic events that create marbles.

Table 1: Principal Limestone-Bearing Geological Formations in Tanzania

Formation Name	Geological Age/Period	Dominant Limestone Type(s)	Key Associated Regions/Basins
Tanga Limestone	Middle Jurassic (Bathonian)	Marine limestone, coralliferous limestone	Tanga Region (Coastal Belt)
Kidugalo Formation	Middle Jurassic (Aalenian-Bajocian)	Oolitic limestone, marl, silty calcareous sandstone	Pwani Region, Ruvu-Tanga sub-basin (Coastal Belt)
Lugoba Formation	Middle Jurassic (Bajocian)	Coralliferous limestone	Pwani Region, Dar es Salaam hinterland (Coastal Belt)
Mtumbei Formation	Middle Jurassic (Bajocian-Bathonian)	Marine limestone (associated with shales)	Lindi Region, Mandawa Basin, Selous Basin (Coastal Belt)
Wazo Hill Deposits	Tertiary	Fossil reef limestone	Dar es Salaam Region (Coastal Belt)
Zanzibar Coral Limestones	Quaternary/Recent	Coral limestone, biogenic calcium carbonate	Zanzibar Archipelago (Unguja, Pemba) (Coastal Belt)
Karoo Supergroup Limestones	Late Carboniferous – Early Jurassic	Lacustrine/palustrine limestone (thin layers)	Tanga Basin, Selous Basin, other Karoo basins (Interior/Coastal)
Mozambique Belt Marbles	Precambrian (Neoproterozoic)	Crystalline limestone (marble)	Morogoro Region, Dodoma Region, other eastern areas
Usagaran System Marbles	Precambrian (Proterozoic)	Crystalline limestone (marble)	Morogoro Region, Southern Highlands
EARS Carbonatites	Cretaceous – Cenozoic	Calcitic/dolomitic carbonatite	Mbeya Region (e.g., Panda Hill, Songwe Scarp)
EARS Travertines	Cenozoic – Recent	Travertine	Mbeya Region (Songwe Valley), potential in Arusha, Manyara etc.

III. Regional Distribution and Characteristics of Limestone Deposits in Tanzania

Limestone occurrences are widespread across Tanzania, with significant deposits and varying characteristics found in numerous administrative regions. The following section details these regional distributions.

1. Tanga Region The Tanga Region, situated in the northern coastal belt of Tanzania, is underlain by Mesozoic (predominantly Middle Jurassic Tanga Limestone) and Cenozoic sedimentary successions. The Tanga Fault is a significant structural feature influencing the geology of this area.

Specific Locations & Deposits: The most notable limestone localities are Pongwe and Amboni, which are key sources for the Tanga Limestone formation. These deposits are crucial for the operations of the Tanga Cement factory.
Limestone Type & Quality: The Tanga Limestone is a Middle Jurassic marine limestone, which includes coralliferous varieties. While detailed chemical analyses for cement grade are not extensively provided, its longstanding use by Tanga Cement implies its suitability for this purpose. Additionally, the Tanga onshore basin is reported to contain dolomitic limestones, which have been noted for their potential as hydrocarbon source rocks.
Primary Use(s): The primary use is cement manufacturing, with Tanga Cement holding a significant market share. Raw high-grade limestone chips are also supplied from Tanga for other purposes.

2. Dar es Salaam Region The Dar es Salaam Region, also part of the coastal belt, is characterized by prominent Cenozoic (Tertiary) fossil reef limestones.

Specific Locations & Deposits: Wazo Hill, located in Tegeta, is a major deposit of Tertiary fossil reef limestone. It rises to approximately 100 meters above sea level and is considered one of the largest carbonate occurrences on the Tanzanian coast, holding substantial limestone reserves. This deposit is extensively quarried by the Tanzania Portland Cement Company (TPCC).
Limestone Type & Quality: The limestone is of a fossil reef type. Its chemical composition is reported to be mainly CaCO3 and SiO2. It is suitable for the production of Portland Composite Cement.
Primary Use(s): The dominant use is cement manufacturing by TPCC (Twiga Cement). Coral limestone sourced from the Dar es Salaam/Coastal region has also found application as a subbase material in road construction projects, though its engineering properties can be variable.

3. Pwani Region (Coastal Region) The Pwani Region lies within the coastal belt and features Mesozoic sedimentary rocks, including the Jurassic-aged Kidugalo and Lugoba Formations, as well as younger Cenozoic deposits. The Ruvu-Tanga sub-basin, a significant geological depression, extends into this region.

Specific Locations & Deposits: The Kidugalo area is known for the Kidugalo Formation, which includes oolitic limestones and ammonite-rich marls and shales. The Lugoba area, including localities like Msata, features exposures of the Lugoba Formation, characterized by coralliferous limestones. In the Bagamoyo District, the Mpiji Borrow Area has been a source of coral limestone used for road subbase.
Limestone Type & Quality: The region hosts oolitic limestones, coralliferous limestones, marls, and coral limestone. It is important to note that the engineering properties of coral limestone from the Mpiji area were found to be problematic for road subbase applications due to issues of softening and swelling upon water absorption, which was linked to the presence of smectite clay within the limestone.
Primary Use(s): There is potential for cement raw materials from the Kidugalo and Lugoba type limestones. Coral limestone has been utilized as a road construction material.

4. Mbeya Region The Mbeya Region’s geology is significantly influenced by the East African Rift System, leading to the presence of carbonatites and extensive travertine deposits. The region also forms part of the Proterozoic Ubendian metamorphic belt.

Specific Locations & Deposits: The Songwe area in Usongwe Division hosts limestone deposits that are mined for cement production by Mbeya Cement Company/Tembo Cement (formerly LafargeHolcim Tanzania). These deposits include calcareous sedimentary rocks, predominantly travertine, found in the Songwe valley, covering an area of approximately 13 km² with thicknesses ranging from 5 to 70 meters. The Kongolo Quarry is operated by TAZARA for quarry products, likely aggregates. The Mbeya Carbonatite (Panda Hill) is a known carbonatite intrusion investigated primarily for pyrochlore. The Mbalizi Carbonatite is another such body where weathered sections yield high phosphate (P2O5) concentrations.
Limestone Type & Quality: Travertine is a key limestone type in the Songwe valley. The limestone utilized for Mbeya Cement is suitable for producing high-quality cement. While chemical analyses of Mbeya pozzolans (volcanic ash used in cement blends) are available, specific detailed analyses for the primary limestone used in cement are not extensively covered in the provided information, though the region clearly possesses lime sources suitable for pozzolanic mixes and cement.
Primary Use(s): The foremost use is cement manufacturing. Travertine is also extracted for dimension stone. Aggregates are produced from quarries like Kongolo. Local sources of lime are also available for agricultural purposes.

5. Mtwara Region Located in the southern part of Tanzania’s coastal belt, the Mtwara Region is characterized by Mesozoic-Cenozoic sedimentary successions and includes part of the Ruvuma-Mandawa sub-basin.

Specific Locations & Deposits: In the Mtwara area, Dangote Cement operates the largest cement plant in Tanzania, which sources its limestone raw material locally. This plant has access to substantial limestone reserves estimated at approximately 500 million tonnes, reported to be sufficient for 149 years of operation.
Limestone Type & Quality: The limestone is suitable for producing high-quality 32.5 and 42.5 grade cements. General assessments of coastal limestone occurrences in Tanzania indicate high quality suitable for lime and cement production. Specific chemical analyses of the Mtwara limestone utilized by Dangote are not detailed beyond its proven suitability for their cement production.
Primary Use(s): The predominant use is cement manufacturing by Dangote Cement.

6. Lindi Region The Lindi Region, also situated on the coastal belt, forms part of the Ruvuma-Mandawa sub-basin and is characterized by the NNW-SSE trending Lindi Fault system. It hosts Mesozoic-Cenozoic sedimentary rocks, including the Mandawa-Mahokonde Beds of Bajocian to Kimmeridgian age, which contain intercalations of oolitic limestones and calcareous sandstones.

Specific Locations & Deposits: The Mandawa Basin is a key geological feature, hosting formations such as the Pindiro Shale, the Mandawa-Mahokonde Beds, and the Tendaguru Beds. The Mtumbei Formation, a limestone unit, is also found within this basin.
Limestone Type & Quality: The region contains oolitic limestones and calcareous sandstones. As with other coastal areas, the limestone is generally considered of a quality suitable for lime and cement production.
Primary Use(s): There is potential for cement and lime production from these deposits.

7. Zanzibar Archipelago (Unguja and Pemba) The islands of Unguja and Pemba, forming the Zanzibar Archipelago, are part of the coastal Cenozoic/Quaternary sedimentary province. Their geology is characterized by coral reef build-ups and associated carbonate sediments.

Specific Locations & Deposits: Limestone occurrences are widespread across the islands. Importantly, recent surveys by the Geological Survey of Tanzania (GST) have identified large deposits of high-quality limestone suitable for cement production. The historic buildings of Stone Town are constructed from local coral ragstone. Sediments along the east coast of Unguja, such as in Chwaka Bay and near Pongwe, are reported to be almost 100% biogenic calcium carbonate.
Limestone Type & Quality: Recent discoveries indicate high-quality limestone suitable for cement. The traditional building material is coral limestone, which is predominantly aragonite and has a high CaO content. Biogenic calcium carbonate sands are also present.
Primary Use(s): There is significant potential for cement production from the newly identified large deposits, which could enhance local self-sufficiency. Coral stone has a long history as a traditional building material.

8. Dodoma Region Located in central Tanzania, the Dodoma Region is geologically complex, forming part of the ancient Archean Tanzania Craton and being flanked by adjacent Proterozoic mobile belts such as the Dodoman Belt and the Mozambique Belt. Recent GST surveys have focused on identifying mineral resources in this region.

Specific Locations & Deposits: In the Kiteto, Chemba, and Chamwino districts, GST has completed geological and geochemical surveys that have led to the discovery of limestone deposits through the identification of mineral veins. Chamwino District is one of the seven administrative districts of the Dodoma Region. The Mpwapwa District is known for occurrences of the mineral scapolite, which can sometimes be associated with metamorphosed limestones or original evaporitic sequences; crystalline limestone is mentioned in relation to the Igawa area, although Igawa itself is in Njombe, the reference draws parallels in metamorphic contexts that include Mpwapwa geology. Areas such as Kondoa, Tarkwa, and Gonga have been identified as having hot springs, suggesting potential for travertine deposits.
Limestone Type & Quality: Detailed information on the quality and specific type of the newly discovered limestone in Kiteto, Chemba, and Chamwino is not yet fully available beyond the confirmation of “discovery of limestone deposits”. Given the metamorphic setting of areas like Mpwapwa, any limestone present is likely to be crystalline limestone or marble. Travertine is a possibility near the identified hot springs.
Primary Use(s): The potential uses for the newly discovered deposits are yet to be specified and will depend on their quality and volume.

9. Morogoro Region The Morogoro Region is situated within the Proterozoic Usagaran System and Mozambique Belt, geological terrains known for their metamorphic rocks.

Specific Locations & Deposits: The Mahenge area is known for limestone (marble) occurrences; this area is also famous for gemstones like spinel, which can form through the contact metamorphism of limestone and dolomite. More broadly, a “white marble deposit of the Morogoro Region” is cited as a significant resource of high-purity limestone and dolomite.
Limestone Type & Quality: The region is characterized by high-purity white marble (a type of crystalline limestone) and dolomite. These deposits are considered to have excellent potential for dimension stone and for refractory grade limestone.
Primary Use(s): The primary uses are for dimension stone. There is also potential for refractory grade limestone and other applications requiring high-purity calcium carbonate.

10. Manyara Region The geology of the Manyara Region is influenced by the East African Rift System, with associated lacustrine sedimentation and volcanic activity.

Specific Locations & Deposits: The Minjingu area in Babati District is well-known for its phosphate rock (MPR) deposits, which occur in lacustrine sediments. Associated with these phosphorites are carbonate minerals, including calcite and dolomite. The Minjingu Quarry, primarily for phosphate, lists calcite and dolomite among the minerals present at the site. Studies of olive green clays (bentonite) at Minjingu note that these clays can be cemented with calcite and some dolomite. The Masware-Babati area has been identified as having hot springs, indicating potential for travertine deposits.
Limestone Type & Quality: Calcite and dolomite are found in association with the phosphate and lacustrine clay deposits. Travertine is also a potential type. The quality of these carbonates is likely variable; some calcite may be related to the alteration or cementation of other sedimentary units rather than forming discrete, mineable limestone beds.
Primary Use(s): Currently, the limestone/calcite in the Minjingu area appears to be more of an associated mineral phase within the phosphate and bentonite deposits rather than a primary quarried commodity for traditional limestone uses. This could change with further detailed assessment.

11. Ruvuma Region Located in southern Tanzania, the Ruvuma Region’s geology may be influenced by extensions of the Karoo Supergroup and the southern reach of coastal sedimentary basins, specifically the Ruvuma-Mandawa sub-basin.

Specific Locations & Deposits: While there is general mention of mineral potential due to its geological setting (e.g., base metals are found in a belt running through Ruvuma ), specific limestone deposits are not well-detailed in the provided information. However, the Mtumbei and Kidugalo Formations (which include limestones) are mentioned in the context of the broader Ruvuma basin, among others.
Limestone Type & Quality: If related to coastal basin extensions, the limestone would likely be sedimentary marine types. If associated with Karoo sequences, they might be thinner, possibly lacustrine limestones. No specific quality data for limestone in the Ruvuma Region is available from the provided sources.
Primary Use(s): The region appears to be largely underexplored specifically for limestone resources based on the available information.

12. Selous Basin / Nyerere National Park This vast area in south-central Tanzania comprises a large interior basin containing Karoo deposits, which may be overlain by younger sediments. The Karoo sequence here includes fluvial, deltaic, and lacustrine deposits. The regional stratigraphy also associates post-rift Middle Jurassic limestones, such as the Kidugalo and Mtumbei Formations, with the Selous Basin.

Specific Locations & Deposits: Preliminary research findings from the GST indicate the existence of limestone, among other minerals, within the Nyerere National Park and the Selous Game Reserve.
Limestone Type & Quality: The specific type and quality of this limestone are not detailed in the initial reports. It could potentially be Karoo-associated lacustrine limestone or extensions of the coastal marine Jurassic limestone formations.
Primary Use(s): Currently at an exploration stage. Any potential exploitation would need to consider the protected status of these areas and be subject to rigorous environmental assessments.

13. Other Regions (Arusha, Singida, Shinyanga, Kagera) These regions exhibit varied geological contexts, including parts of the Tanzania Craton, Proterozoic belts, and areas influenced by the East African Rift System.

Specific Locations & Deposits: In the Arusha, Singida, and Shinyanga regions, GST mineral surveys have identified hot springs. These are noted for their geothermal potential but also suggest possibilities for associated travertine deposits. In the Kagera Region, specifically Biharamulo District, GST surveys have revealed kaolin deposits; there is no specific mention of limestone discoveries in this particular survey, but it was part of broader regional mineral assessment efforts.
Limestone Type & Quality: If associated with the identified hot springs, the limestone type would likely be travertine. Other potential occurrences in these regions are not detailed.
Primary Use(s): Currently at an exploratory stage for limestone resources.

Recent activities by the Geological Survey of Tanzania, as reported around March 2025, indicate a significant expansion in the known footprint of limestone resources within the country. These efforts are particularly notable in areas that were previously less explored for limestone, such as the Zanzibar archipelago and several districts within the Dodoma Region (namely Kiteto, Chemba, and Chamwino), as well as preliminary findings within the Selous Game Reserve/Nyerere National Park. This active pursuit by GST to delineate new mineral resources, including limestone, beyond the traditionally recognized coastal belts and established cement-producing areas, carries important implications. It suggests a potential for decentralizing limestone resource availability across Tanzania, which could, in turn, foster the development of new local industries and reduce regional disparities in access to this essential raw material.

The establishment and concentration of major cement manufacturing plants in Tanzania show a direct correlation with the proximity to substantial and geologically distinct limestone deposits. For instance, Tanga Cement utilizes the Jurassic marine limestones of the Tanga Limestone formation. The Tanzania Portland Cement Company (TPCC) at Wazo Hill exploits Tertiary fossil reef limestones. Cement plants in the Mbeya Region, such as Tembo Cement (formerly Lafarge), rely on the Songwe deposits, which include Rift-related travertine and potentially carbonatitic limestones. Dangote Cement in Mtwara operates with access to extensive local limestone reserves, likely of Mesozoic or Cenozoic coastal origin. This pattern underscores that the primary economic driver for large-scale limestone exploitation in Tanzania has historically been, and continues to be, the demand from the cement industry. The geological suitability and sheer volume of limestone at these specific locations are paramount, dictating regional industrial development centered around these critical resources.

Table 2: Regional Summary of Significant Limestone Occurrences in Tanzania

Region	Specific Location/Deposit Name	Geological Setting/Formation	Predominant Limestone Type(s)	Noted Quality/Characteristics	Primary Use(s)/Potential
Tanga	Pongwe, Amboni	Coastal Belt; Middle Jurassic Tanga Limestone	Marine limestone, coralliferous	Suitable for cement; high-grade chips	Cement manufacturing, aggregates
Dar es Salaam	Wazo Hill (Tegeta)	Coastal Belt; Tertiary Reef Limestone	Fossil reef limestone	Mainly CaCO3 & SiO2; suitable for cement	Cement manufacturing
Pwani (Coastal)	Kidugalo, Lugoba (Msata), Mpiji	Coastal Belt; Jurassic Kidugalo & Lugoba Fms., Cenozoic coral limestone	Oolitic, coralliferous, coral limestone, marl	Variable; some coral limestone poor for subbase (clay content)	Potential cement raw material, road subbase
Mbeya	Songwe Valley, Kongolo Quarry, Panda Hill, Mbalizi Carbonatite	EARS influence; Travertine, Carbonatites; Ubendian Belt	Travertine, carbonatitic limestone	Suitable for cement (Songwe); dimension stone (travertine)	Cement, dimension stone, aggregates, agricultural lime
Mtwara	Mtwara area (Dangote plant)	Coastal Belt; Mesozoic-Cenozoic sediments; Ruvuma-Mandawa sub-basin	Marine sedimentary limestone	Suitable for high-quality 32.5 & 42.5 grade cement; large reserves (~500MT)	Cement manufacturing
Lindi	Mandawa Basin	Coastal Belt; Mesozoic-Cenozoic sediments; Mandawa-Mahokonde Beds, Mtumbei Fm.	Oolitic limestone, calcareous sandstone	Generally suitable for lime/cement (coastal type)	Potential cement/lime production
Zanzibar	Archipelago-wide	Coastal Cenozoic/Quaternary; Coral reef build-ups	Coral limestone, biogenic CaCO3, high-quality limestone	High CaO, aragonite (coral); newly found deposits suitable for cement	Potential cement production, traditional building material
Dodoma	Kiteto, Chemba, Chamwino districts; Mpwapwa; Kondoa, Tarkwa	Tanzania Craton & Proterozoic belts; EARS influence	Limestone (new discoveries), crystalline limestone/marble, travertine (potential)	Details pending for new discoveries; hot springs indicate travertine potential	Exploration stage for new discoveries
Morogoro	Mahenge area, general regional deposits	Precambrian Usagaran System/Mozambique Belt	High-purity white marble (crystalline limestone), dolomite	High purity, suitable for dimension stone & refractory grade	Dimension stone, refractory limestone, high-purity applications
Manyara	Minjingu (Babati Dist.), Masware-Babati	EARS influence; Lacustrine sediments, volcanic activity	Calcite, dolomite (assoc. with phosphate/bentonite), travertine (potential)	Variable; associated with other minerals	Associated mineral with phosphate; potential travertine
Ruvuma	General regional potential	Karoo Supergroup extensions, southern coastal basins (Ruvuma-Mandawa sub-basin)	Sedimentary (marine/lacustrine)	Unspecified	Largely unexplored for limestone
Selous/Nyerere	Nyerere Nat. Park, Selous Game Reserve	Interior Karoo Basin, potential coastal Jurassic extensions	Limestone (preliminary findings)	Unspecified	Exploration stage; environmentally sensitive

IV. Typology and Geochemical Overview of Tanzanian Limestones

Tanzanian limestones exhibit considerable diversity in terms of their mode of formation, texture, mineralogy, and chemical composition, reflecting the varied geological environments in which they occur.

A. Classification of Limestone Types Found

Based on available geological descriptions, the following principal types of limestone are found in Tanzania:

Oolitic Limestones: These are composed primarily of ooids, which are small, spherical or ellipsoidal, sand-sized grains (typically <2 mm in diameter) formed by the concentric precipitation of calcium carbonate (calcite or aragonite) around a nucleus, such as a tiny shell fragment or quartz grain. Oolitic limestones typically form in shallow, agitated, warm marine environments with strong currents. In Tanzania, oolitic limestones are noted within the Middle Jurassic Kidugalo Formation (e.g., the “Kidugalo Oolite”) in the Pwani Region and as part of the Mandawa-Mahokonde Beds in the Lindi Region.
Coralline/Reef Limestones: These limestones are formed from the accumulation of skeletal remains of corals and other reef-building organisms, along with associated carbonate detritus, in warm, clear, shallow marine waters. They are prominent in several geological successions in Tanzania. Examples include parts of the Middle Jurassic Tanga Limestone and Lugoba Formation , the Tertiary fossil reef limestones extensively quarried at Wazo Hill near Dar es Salaam , and the Quaternary to Recent coral limestones and coral rag used historically and found abundantly in the Zanzibar archipelago.
Crystalline Limestones (Marbles): These are carbonate rocks that have undergone metamorphism, resulting in the recrystallization of the original calcite or dolomite into a typically coarser, interlocking crystalline texture. Marbles are found in Tanzania’s Precambrian metamorphic terrains. Notable examples include the high-purity white marbles of the Morogoro Region, hosted within the Usagaran System and Mozambique Belt.
Travertine: This is a form of freshwater limestone deposited by the precipitation of calcium carbonate from mineral-rich waters, often associated with hot springs or waterfalls. In Tanzania, travertine deposits are linked to geothermal activity within the East African Rift System. Significant travertine occurrences are found and mined in the Songwe Valley, Mbeya Region. Potential for further travertine discoveries exists in other areas with known hot springs, such as parts of Arusha, Manyara, Dodoma, Singida, and Shinyanga regions.
Carbonatitic Limestones: These are unusual igneous rocks composed of more than 50% primary carbonate minerals, typically calcite and/or dolomite. They are associated with specific tectonic settings, often continental rifts. Examples in Tanzania include the Mbeya Carbonatite (Panda Hill) and the Songwe Scarp Carbonatite, both in the Mbeya Region. These can be sources of either calcitic or dolomitic limestone.
Lacustrine/Thinly Bedded Limestones: These limestones are interpreted to have formed in freshwater lakes or swamps. They occur periodically as relatively thin layers within the predominantly terrestrial sequences of the Karoo Supergroup.
Biogenic Calcium Carbonate Sands/Sediments: These are unconsolidated or poorly consolidated accumulations of carbonate material derived from the skeletal remains of marine organisms. An example is the modern sediments found on the east coast of Zanzibar, which are reported to be almost entirely composed of biogenic calcium carbonate.

B. Summary of Known Quality Parameters

The suitability of Tanzanian limestones for various applications is determined by their physical and chemical properties. Key quality indicators include:

Cement Grade Suitability: This is a primary consideration due to the large demand from the cement industry. Limestones from Tanga (Pongwe), Wazo Hill, Mbeya (Songwe area), Mtwara, and newly identified deposits in Zanzibar are explicitly mentioned as being suitable for cement manufacturing. High-quality limestone (implying high CaCO3 content and appropriate levels of other oxides like SiO2, Al2O3, and Fe2O3) is preferred for producing better quality cement.
High-Calcium / High-Purity: This refers to limestones with a very high percentage of calcium carbonate, typically >95% CaCO3. The white marble deposits of the Morogoro Region are specifically described as being of high purity. Such limestones are crucial for producing chemical-grade lime, and can be used as fillers in industries like paper and paint, or in glass manufacturing.
Dolomitic Limestone: These are carbonate rocks containing a significant proportion of the mineral dolomite (CaMg(CO3)2). Dolomitic limestone is reported from the Morogoro Region and associated with deposits in the Minjingu area (Manyara Region). In the Tanga Basin, dolomitic limestone has also been noted as a potential hydrocarbon source rock.
Suitability for Dimension Stone: This depends on factors like color, texture, soundness, and the ability to take a polish. Travertine from the Songwe valley in Mbeya and the marbles from the Morogoro Region are utilized or have good potential as dimension stone.
Agricultural Lime: For agricultural use, the key property is the limestone’s ability to neutralize soil acidity, often expressed as its calcium carbonate equivalent (CCE) or neutralizing value. Specific quality parameters are not detailed extensively, but the use of local limestone for this purpose is implied in Mbeya and by commercial producers.
Presence of Impurities: The type and amount of impurities significantly affect limestone quality. Silica (SiO2) is a common impurity, noted, for example, in the Wazo Hill limestone. Clay minerals, such as smectite found in some coral limestones in the Pwani Region (Mpiji area), can have deleterious effects on the engineering properties of the material, particularly its stability when exposed to water.

C. Brief on Chemical Composition for Key Deposits

Detailed, publicly available chemical analyses for many Tanzanian limestone deposits are somewhat limited in the provided information, but some compositional aspects are noted:

Wazo Hill Limestone (Dar es Salaam): The chemical composition is stated to be mainly calcium carbonate (CaCO3) and silica (SiO2).
Zanzibar Coral Stone: Chemical analysis (XRD and XRF) of coral stones from Zanzibar’s Stone Town demonstrates a high calcium oxide (CaO) content, with the predominant carbonate mineral being aragonite (a polymorph of CaCO3).
General Limestone Composition: By definition, limestone consists of 50% or more of calcite and dolomite, with calcite usually predominating. High-calcium limestone should contain at least 95% CaCO3.
Mbeya Region Carbonatites/Travertine: The Songwe Scarp carbonatite is associated with phosphate (P2O5) and potash (K2O) mineralization. Chemical data for Mbeya pozzolans (volcanic ash, not limestone) show typical silicate compositions (SiO2, Al2O3, Fe2O3, CaO, MgO, etc.).
Tanga Limestone: Specific chemical analyses are not provided, but its long-term use in cement production by Tanga Cement indicates a composition suitable for this industry.
Mtwara Limestone (Dangote): Similarly, while specific chemical data is not detailed, the plant produces 32.5 and 42.5 grade cements, which implies that the limestone feedstock meets the required chemical specifications for these products.

While “cement-grade” is a frequently used descriptor for many Tanzanian limestones, the availability of comprehensive public domain geochemical data—such as full major and minor oxide analyses, and trace element concentrations—appears to be somewhat restricted for numerous specific deposits. This observation suggests a potential information gap, particularly for assessing the suitability of these limestones for more specialized industrial applications beyond bulk cement manufacturing. Applications like chemical lime production, high-purity fillers for pharmaceuticals or food-grade products, or use in the glass industry, demand very precise knowledge of limestone chemistry, including extremely low levels of deleterious elements like iron, magnesium (for high-calcium lime), phosphorus, and sulfur. The general statements about suitability for cement, or mentions of major components like CaCO3 and SiO2 (as for Wazo Hill ), are often insufficient for these niche markets. The absence of such widespread, detailed data in the available information implies that while the broad utility of many deposits is recognized, finer characterization necessary for diverse industrial markets might require further dedicated investigation or is currently held as proprietary information by operating companies.

Furthermore, the specific mineralogical form of calcium carbonate present in Tanzanian limestones, notably the distinction between calcite and aragonite (as identified in Zanzibar coral stone ), can significantly influence their properties and potential uses, often beyond what is indicated by bulk chemical composition alone. Aragonite is a polymorph of CaCO3 that typically forms in specific marine environments, such as in the skeletons of modern corals. It is geologically metastable and tends to alter to the more stable calcite form over geological time or under conditions of diagenesis. Its presence in younger deposits like the Quaternary coral stones of Zanzibar is therefore expected. Aragonite can exhibit different physical properties (e.g., crystal habit, density, cleavage) compared to calcite, which may affect its behavior during processing or its performance in certain end-uses. For instance, aragonite’s potentially higher reactivity might be advantageous in some chemical processes or for rapid action as agricultural lime. However, its long-term stability could be a concern for applications like dimension stone if the material is prone to alteration, unless appropriate conservation measures are taken. This level of mineralogical detail is often overlooked when assessments are based solely on bulk chemical analysis, yet it can be critical for optimizing the use of these natural resources.

V. Economic Significance and Utilization of Limestone in Tanzania

Limestone is a cornerstone of Tanzania’s industrial minerals sector, with its exploitation driven primarily by the construction industry, particularly cement manufacturing. However, its uses extend to agriculture, aggregates, and dimension stone, reflecting a broadening economic base for this versatile resource.

A. Cement Manufacturing: Dominant Use, Key Production Centers, and Limestone Sourcing

Cement manufacturing is by far the dominant consumer of limestone in Tanzania. Limestone serves as the principal raw material, providing the essential calcium carbonate (CaCO3) which, upon calcination, yields calcium oxide (CaO), the primary component of cement clinker. Tanzania has a rapidly growing cement business and is a leading producer in East Africa, driven by domestic infrastructure development and housing projects.

Several key production centers are strategically located near substantial limestone deposits:

Tanga Cement (Simba Cement) in the Tanga Region utilizes the Jurassic Tanga Limestone, with quarries in areas like Pongwe.
Tanzania Portland Cement Company (TPCC – Twiga Cement), based in the Dar es Salaam Region, quarries Tertiary fossil reef limestone from the extensive Wazo Hill deposit.
Mbeya Cement Company (Tembo Cement, formerly LafargeHolcim) in the Mbeya Region sources its limestone from the Songwe area, which includes travertine deposits.
Dangote Cement operates the largest cement factory in Tanzania, located in the Mtwara Region. This plant relies on vast local limestone reserves, estimated at around 500 million tonnes.

The quality of limestone is critical for cement manufacturing, requiring high CaCO3 content and controlled levels of impurities such as SiO2, Al2O3, and Fe2O3. Recent discoveries of high-quality limestone in Zanzibar by the Geological Survey of Tanzania (GST) offer significant potential for establishing new cement production facilities on the islands. This could enhance local self-sufficiency, reduce reliance on imported cement, and potentially lower construction costs in Zanzibar.

B. Agricultural Applications: Use as Soil Conditioner (Agricultural Lime)

Limestone plays a vital role in agriculture as a soil conditioner, commonly referred to as agricultural lime. Its application helps to neutralize acidic soils, thereby improving soil pH, enhancing nutrient availability to plants, and promoting better soil structure. Several regions in Tanzania suffer from soil acidity, which adversely impacts crop productivity. The application of lime has been shown to significantly improve yields for key crops such as maize and beans. Commercial production of agricultural lime occurs in Tanzania. For example, ABM Equipment Services Ltd, based in Tanga, manufactures and supplies products like “ABM Agricultural Lime” and “ABM Dolomitic Lime” (which also provides magnesium). The Mbeya region also has local lime sources that can be utilized, sometimes in conjunction with locally sourced phosphate rock, for soil amendment programs. Despite its benefits, challenges in the widespread use of agricultural lime include its bulkiness, the relatively large quantities required per hectare (often around 1 tonne/ha), and the associated transportation and application costs.

C. Construction Aggregates: Limestone as a Source Material

Crushed limestone is an important source material for construction aggregates, used in various sizes for both building and road construction projects. Companies like Kibogate Tanzania Limited are known suppliers of crushed limestone aggregates in different gradations. Aggregate Crushing Industries Ltd, operating in the Lugoba area (Pwani Region), also supplies crushed limestone among other aggregate types. The demand for limestone aggregates is also evident from investments in crushing capacity. For instance, a Tanzanian client recently acquired a 100-120 tonnes per hour (TPH) limestone crushing plant, with the output intended for both cement production (fine particles) and construction material (0-5mm, 5-10mm, 10-20mm aggregates). Coral limestone, particularly from coastal areas, has also been used as a subbase material in road projects, such as the Wazo Hill-Bagamoyo road. However, the engineering properties of some coral limestones can be variable and problematic if they contain impurities like expansive clays, which can lead to pavement instability.

D. Dimension Stone: Marble and Travertine Quarries and Potential

Certain types of Tanzanian limestone, particularly marbles and travertines, are valued as dimension stone due to their aesthetic qualities and durability. The Morogoro Region is renowned for its high-purity white marble deposits, which are considered to have excellent potential for the dimension stone market. ABM Equipment Services in Tanga also lists raw white marble stones among its supplied products. Travertine deposits in the Songwe valley (Mbeya Region) are actively mined for use as dimension stones.

E. Other Industrial Uses

Beyond the major applications, limestone has potential for various other industrial uses in Tanzania, although data on current exploitation levels for these niche markets is less comprehensive. Globally, limestone is used in the iron and steel industry (as a flux), in chemical industries (for lime production, which has numerous applications), in water treatment processes, and as a filler in products like paper, paint, plastics, and rubber. The high-purity marbles of Morogoro, for example, could be suitable for producing refractory grade limestone, which is used in high-temperature applications. Dolomite, which often occurs in association with limestone or as distinct deposits (e.g., in Morogoro, Minjingu), also has various industrial applications, including as a flux, in glass manufacturing, and as a source of magnesium. Kusini Gateway Industrial Park is listed as a supplier of dolomite lumps and powder.

While cement production is clearly the dominant consumer of limestone in Tanzania, the available information points to an emerging and increasingly diverse, albeit smaller-scale, utilization of this resource in agriculture, construction aggregates, and the dimension stone industry. This diversification, though less prominent than the cement sector, signals a growing recognition and exploitation of limestone’s varied properties to serve different markets. This trend suggests a broadening of the economic base associated with limestone, moving beyond a single primary application.

The logistical challenges and significant costs associated with transporting limestone, a bulky and relatively low-value commodity in its raw state, play a crucial role in determining the economic viability of its various applications. This is particularly true for products like agricultural lime and construction aggregates, where the end-product value may not support long-distance haulage. This constraint is explicitly highlighted by the fact that transportation can constitute approximately 17% of the overall project cost for agricultural lime initiatives , and cement manufacturers prioritize local sourcing of raw materials to minimize transport expenses. Consequently, for uses where the market price of the final product is not as high as that of cement, transporting limestone over extensive distances may render operations uneconomical. This economic reality could create opportunities for the development of localized, smaller-scale limestone quarries. Such operations could cater to specific local demands for agricultural lime or construction aggregates, provided that geologically suitable deposits are identified in proximity to these demand centers, even if these deposits are not large or pure enough to sustain a major cement plant.

Table 3: Overview of Limestone Utilization in Tanzania

Primary Use	Key Regions/Deposits Utilized	Examples of Major Operations/Suppliers (if available)	Indication of Scale
Cement Manufacturing	Tanga, Dar es Salaam (Wazo Hill), Mbeya (Songwe), Mtwara, Zanzibar (potential)	Tanga Cement, TPCC (Twiga), Tembo Cement (Mbeya Cement), Dangote Cement	Large
Agricultural Lime	Tanga, Mbeya, other regions with acidic soils	ABM Equipment Services Ltd, local sources in Mbeya	Small to Medium
Construction Aggregates	Pwani (Lugoba), Dar es Salaam (coral), Mbeya (Kongolo)	Kibogate Tanzania Ltd, Aggregate Crushing Industries Ltd, TAZARA (Kongolo)	Small to Medium
Dimension Stone	Morogoro (marble), Mbeya (travertine), Tanga (marble)	ABM Equipment Services (marble); mining of travertine in Songwe	Small to Medium
Other Industrial	Morogoro (refractory potential), general (fillers, chemical)	Kusini Gateway (dolomite); potential for high-purity uses from Morogoro marble	Mostly Potential/Small

VI. Data Sources and Future Exploration Perspectives

The understanding and development of Tanzania’s limestone resources rely heavily on the activities of governmental bodies responsible for geological surveys and mineral sector management, as well as ongoing exploration efforts.

A. The Role of the Geological Survey of Tanzania (GST)

1. Mandate and Historical Context: The Geological Survey of Tanzania (GST), established in 1925 under the British colonial administration, is the principal governmental scientific institution mandated to investigate the nation’s geology, mineral resources, and potential geological hazards. Its primary objective has been to provide essential geological information acquired through systematic geological mapping, reconnaissance and detailed mineral exploration, and prospecting for groundwater resources. GST operates as a scientific department under the Ministry of Minerals.
2. Geological Mapping: A significant achievement of GST has been the geological mapping of a vast portion of the country. Approximately 94-95% of Tanzania has been geologically mapped at various scales, and these data are available in the form of published Quarter Degree Sheets (QDS). The country is divided into 322 such QDS blocks, each covering an area of nearly 3000 square kilometers. A “Geology and Mineral map of Tanzania (2008)” is a key reference map produced by or incorporating GST data. However, it is recognized that many of the existing geological maps were produced during regional surveys conducted between the 1930s and 1970s. As such, these maps, while foundational, often warrant updates using modern geological concepts, remote sensing techniques, and analytical methods. GST is actively engaged in this updating process, for example, through re-mapping projects like that of the Handeni QDS 148.
3. Geochemical and Geophysical Surveys: GST also undertakes systematic geochemical and geophysical surveys to enhance the understanding of subsurface geology and mineral potential. Low-resolution aerial geophysical data (typically magnetic and radiometric, at 1 km line spacing) is available for the entire nation. More detailed, high-resolution aerial geophysical surveys (200-250m line spacing) currently cover approximately 16% of the country. GST has ambitious plans to increase this high-resolution coverage to 34%, intending to use aircraft-borne survey methods for more rapid data acquisition. Geochemical survey data, involving the systematic collection and analysis of samples of soil, stream sediment, or rock, is available for about 19% of the country. These integrated surveys are instrumental in identifying mineral veins and delineating areas with potential for various mineral deposits, including the recent limestone discoveries.
4. Geological and Mineral Information System (GMIS): As the custodian of all national geoscientific data, GST manages the Geological and Mineral Information System (GMIS). This system serves as a centralized, standardized database for geological, geophysical, geochemical, and mineral occurrence information, and is intended to be accessible to the public and potential investors. This information is crucial for guiding exploration efforts by the private sector.
5. Recent Discoveries and Ongoing Work: Recent announcements from GST (as of March 2025 reports) highlight significant new limestone discoveries, underscoring the agency’s ongoing contribution to resource delineation:
- Zanzibar: Identification of high-quality limestone suitable for cement production.
- Dodoma Region: Discovery of limestone deposits in the Kiteto, Chemba, and Chamwino districts following targeted geological and geochemical surveys.
- Nyerere National Park / Selous Game Reserve: Preliminary research findings indicate the existence of limestone within these protected areas. To support its analytical capabilities, GST also plans to construct a new, state-of-the-art laboratory in Dodoma. This facility is expected to enhance the analysis of mineral samples, boost research activities, and promote the overall growth of the mining sector.

B. Ministry of Minerals

1. Online Mining Cadastre Transactional Portal (Madini Portal – portal.madini.go.tz): The Ministry of Minerals, through the Mining Commission, has developed and manages the Online Mining Cadastre Transactional Portal (often referred to as the “Madini Portal”). This digital platform is designed to streamline the administration of mining rights and licenses in Tanzania, covering applications for Prospecting Licences (PLs), Mining Licences (MLs), Special Mining Licences (SMLs), dealer licenses, and other mineral rights. The portal is a comprehensive system that maintains geospatial records of all mining areas, tracks the status and compliance of licenses, processes fee payments, and helps to prevent the overlapping of claims. It aims to enhance transparency in license allocation, improve investor access to geological information, strengthen regulatory oversight, and enable more efficient management of the country’s mineral resources. A key feature is its map viewer, which allows users to visualize active and pending applications, protected zones, areas with known mineral potential, administrative boundaries, forest and game reserves, and other relevant topographic features.
2. Policy and Regulatory Framework: The Ministry of Minerals is responsible for formulating and implementing policies and regulations that govern the mining sector. The Mineral Policy of 2009 and the subsequent Mineral (Value Addition) Regulations of 2020 are key instruments that guide the sector, with an emphasis on promoting local processing and value addition to mineral resources extracted in Tanzania. The Ministry also periodically releases investor guides and mineral production statistics, which include information on industrial minerals like limestone, sometimes with data on discovered tonnages.

C. Potential for Further Exploration and Resource Delineation

Despite Tanzania’s rich mineral endowment, many resources, including limestone, remain poorly explored or underexplored. GST’s ongoing geological, geophysical, and geochemical survey programs are crucial for systematically assessing the country’s mineral potential and identifying new deposits. The Phanerozoic geological terranes—which include the coastal sedimentary basins, the Karoo Supergroup sediments, and the volcanic and sedimentary sequences associated with the East African Rift System—are recognized as being particularly rich in limestone, alongside other minerals such as coal, natural gas, and various industrial minerals. The Ministry of Minerals has designed priority blocks for high-resolution airborne geophysical surveys. These surveys are strategically planned to target areas with high potential for discovering new deposits of critical and strategic minerals, including industrial minerals like limestone, driven by increasing demand for these commodities.

There is a discernible strategic impetus from Tanzanian authorities, encompassing both the Geological Survey of Tanzania and the Ministry of Minerals, to significantly enhance the coverage, quality, and accessibility of geoscientific data. This commitment is fundamental for attracting private sector investment into the mineral sector and for enabling further discoveries of limestone and other valuable mineral resources. GST’s ongoing efforts to expand high-resolution geophysical survey coverage , update and refine geological maps (QDS) using modern techniques , and establish advanced laboratory facilities for mineral analysis are key components of this drive. Complementing these technical initiatives is the Ministry’s development and implementation of the Online Mining Cadastre Portal , which aims to modernize mineral rights administration and improve data transparency. Such a systematic and modernized approach to managing and disseminating geoscientific information is vital for de-risking exploration activities and promoting the informed and sustainable development of Tanzania’s diverse mineral resources, including its widespread limestone occurrences.

While broad-scale geological mapping has been accomplished for most of Tanzania, and geophysical surveys provide regional subsurface insights, a critical factor for the future comprehensive development of the country’s limestone resources—especially for diverse industrial applications that go beyond bulk use in cement—will be the systematic acquisition, interpretation, and public dissemination of detailed geochemical and quality data for both known and newly discovered deposits. General geological maps and regional geophysical surveys are effective in identifying potential limestone-bearing areas. However, as previously noted, specific industrial applications such as chemical lime, pharmaceuticals, high-grade fillers, or specialized construction materials require precise knowledge of the limestone’s purity (e.g., high CaCO3 content, low levels of deleterious elements like Fe2O3, MgO for certain uses, P2O5, S), its physical properties (e.g., whiteness, hardness, porosity), and its reactivity. The planned state-of-the-art GST laboratory in Dodoma could play a pivotal role in addressing this need, provided its analytical capabilities are geared towards the comprehensive characterization of industrial minerals like limestone. Crucially, these detailed findings would need to be systematically integrated into publicly accessible databases, such as the GMIS, to be of maximum benefit to potential investors and end-users. This level of detailed characterization moves beyond simply locating limestone to fundamentally understanding its precise quality and thus its true economic value across a spectrum of potential applications.

VII. Conclusion and Strategic Recommendations

A. Recapitulation of the Widespread and Geologically Diverse Nature of Limestone Resources in Tanzania

This review confirms that Tanzania possesses abundant and geologically diverse limestone resources. These deposits are distributed across various regions of the country, from the extensive Mesozoic-Cenozoic marine sedimentary limestones of the coastal belt and Zanzibar archipelago, to the ancient Precambrian crystalline marbles of the metamorphic terrains, the periodically occurring continental limestones within the Karoo Supergroup, and the Cenozoic carbonatites and travertine deposits associated with the East African Rift System. This geological variety results in a wide spectrum of limestone types and qualities, offering potential for a range of economic applications.

B. Summary of Key Regions and Deposit Types with High Economic or Strategic Importance

Several regions and deposit types stand out due to their current economic contribution or high strategic potential:

Coastal Regions (Tanga, Dar es Salaam, Pwani, Mtwara, Lindi, Zanzibar): These are paramount for their extensive sedimentary limestones, which form the backbone of Tanzania’s cement industry. Recent discoveries in Zanzibar highlight new potential in this sub-sector.
Morogoro Region: Known for its high-purity white marbles, offering significant value for dimension stone and specialized industrial applications requiring high-grade calcium carbonate.
Mbeya Region: Hosts important travertine deposits used for cement and dimension stone, as well as carbonatite-associated carbonates.
Dodoma Region and Selous/Nyerere National Park: Emerging areas with newly identified limestone potential, requiring further investigation to ascertain their economic viability and characteristics.

C. Detailed Recommendations

To optimize the exploration, development, and utilization of Tanzania’s limestone resources, the following strategic recommendations are proposed:

1. Targeted Geological Exploration and Resource Quantification:
- Prioritize detailed geological mapping (at scales more refined than the standard QDS), systematic drilling programs, and comprehensive quality assessment in areas with recently discovered limestone potential, particularly in Zanzibar, the Kiteto, Chemba, and Chamwino districts of Dodoma Region, and within the Selous/Nyerere National Park (subject to environmental regulations). The objective should be to accurately quantify reserves and thoroughly characterize the limestone.
- Initiate focused investigations into the economic potential of Karoo-hosted limestones. These are currently underexplored compared to coastal deposits but could offer local sources for agriculture or construction if suitable quality and volume are identified.
- Systematically evaluate Precambrian marble deposits beyond the well-known Morogoro occurrences. Other areas within the Mozambique Belt and Usagaran System may host marbles suitable for dimension stone or high-purity industrial applications.
- Actively explore the potential for EARS-associated travertine deposits in regions identified with significant geothermal activity, such as parts of Arusha, Manyara, Singida, Shinyanga, and Dodoma regions, as these can provide valuable resources for local construction and lime production.
2. Enhancement of Geoscientific Databases and Accessibility (GST & Ministry of Minerals):
- Ensure that the new GST laboratory in Dodoma is equipped with advanced analytical capabilities for the detailed geochemical characterization of limestone. This should include analyses for full major and minor oxides, trace elements, whiteness, brightness, and reactivity (e.g., for agricultural lime). Crucially, this detailed data should be systematically cataloged and made publicly available through the Geological and Mineral Information System (GMIS).
- Continue and accelerate high-resolution geophysical and geochemical survey programs across the country, incorporating specific targeting criteria for industrial minerals, including diverse types of limestone.
- Enhance the functionality and data richness of the Online Mining Cadastre Portal (Madini Portal). This should include more user-friendly search capabilities for specific mineral rights related to industrial minerals like limestone, and easily accessible geospatial data layers showing licensed areas, known deposits, and areas with high exploration potential for limestone.
3. Strategies for Sustainable Development and Value Addition:
- Actively promote private sector investment in local value addition for limestone, moving beyond basic quarrying and crushing for cement. This could include facilities for producing micronized limestone for fillers, hydrated lime, precipitated calcium carbonate (PCC), and other specialized products, contingent on the identification of suitable quality raw material.
- Support and strengthen the agricultural lime sector by establishing and enforcing quality control standards for agricultural lime products and by working with stakeholders to improve distribution networks to reach farmers in regions with acidic soils.
- Encourage the use of locally sourced dimension stone (marble, travertine) in domestic construction projects to reduce reliance on imported materials, stimulate local industry, and showcase Tanzania’s natural stone resources.
- Develop, implement, and rigorously enforce clear environmental and social governance (ESG) guidelines for all limestone quarrying and processing operations. This is essential to minimize environmental impacts (e.g., dust, noise, water quality, land disturbance) and address community concerns, particularly for operations near residential areas (as exemplified by historical issues at Wazo Hill regarding dust and blasting vibrations ).
4. Addressing Data Gaps for Specific Limestone Characteristics:
- Initiate a national-level program for the systematic geochemical and mineralogical characterization of key limestone deposits across all geological settings. The aim should be to create a comprehensive, publicly accessible database detailing their suitability for a wide range of industrial applications, well beyond just cement raw material.
- Conduct thorough market studies to identify existing and potential domestic, regional (East African Community), and international markets for different grades and types of Tanzanian limestone products. The findings of these studies should guide targeted resource development and investment promotion.
- Support research into the engineering properties of different Tanzanian limestone types intended for use as construction aggregates. This will ensure appropriate application, optimize performance in infrastructure projects, and help avoid costly failures, such as those reported with certain coral limestones used as road subbase.

The diverse geological occurrences of limestone in Tanzania suggest a much wider range of qualities and potential applications than are currently being exploited, with the present focus heavily skewed towards cement production. A national limestone development strategy that effectively integrates detailed geological assessment, comprehensive market analysis, and strategic infrastructure planning could unlock significant additional economic potential. Such a strategy would involve the Geological Survey of Tanzania focusing on the detailed characterization of different limestone types to identify their optimal uses. The Ministry of Minerals could then facilitate targeted investment in appropriate processing technologies for these varied types. Concurrently, market analysis would identify demand for non-cement limestone products, both domestically and for export. Finally, targeted infrastructure development, including transport and energy, would be necessary to support geographically dispersed operations, particularly for deposits located away from existing industrial hubs. This holistic and coordinated approach would maximize the value derived from Tanzania’s rich and varied limestone endowment, fostering industrial diversification and contributing to balanced regional development.

Sources

Government and Institutional Sources

Geological Survey of Tanzania (GST): https://www.gst.go.tz
Ministry of Minerals (TMIC Magazine): https://www.madini.go.tz
Tanzania Mining Commission (License Types): https://tumemadini.eganet.go.tz
Petroleum Upstream Regulatory Authority (PURA): https://www.pura.go.tz
UONGOZI Institute – Strategic Minerals in Tanzania: https://www.uongozi.or.tz
Tanzania Trade Development Authority (TanTrade): https://www.tantrade.go.tz
Tanzania Consulate in Denmark – Natural Resources: https://www.tanzaniaconsulate.dk
Investor’s Guide – Tanzania Mining Sector 2024: https://www.madini.go.tz

Kilimo Kwanza

Limestone Resources of Tanzania: A Comprehensive Geological and Economic Review

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Kilimokwanza

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Government and Institutional Sources

Academic & Scientific Sources

News & Media

Industry & Market Sources

Export & Trade Platforms

Research & Innovation

Additional References

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About The Author

Kilimokwanza

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