Limestone, Dolomite and Magnesite
Geography › Mineral and Energy Resources · Topic 21.14
Limestone, dolomite and magnesite are carbonate rocks mined in bulk for industry. Limestone, calcium carbonate, is the main raw material of cement and a flux in steelmaking. Dolomite, a calcium-magnesium carbonate, is a flux and a refractory. Magnesite, magnesium carbonate, makes heat-resistant bricks for furnaces. Limestone is widely spread in India, with large deposits in Rajasthan, Madhya Pradesh, Andhra Pradesh, Gujarat and Karnataka, while magnesite is mainly in Uttarakhand and Tamil Nadu.
5 min read · UPSC Prelims · Geography · Mineral and Energy Resources
At a Glance
- Limestone Calcium carbonate; cement and flux
- Dolomite Calcium magnesium carbonate; flux
- Magnesite Magnesium carbonate; refractory
- Limestone states Rajasthan, Madhya Pradesh, Andhra Pradesh, Gujarat, Karnataka
- Magnesite states Uttarakhand, Tamil Nadu
- Exam link UPSC Prelims, Geography: Mineral and Energy Resources
Where Does It Fit?
This is the fourteenth topic of the macro on mineral and energy resources. The previous topic covered graphite and diamond, and this one covers the carbonate rocks used in construction and steel. The next topic covers asbestos, kyanite and gypsum. Previous topic: Graphite and Diamond. Next topic: Asbestos, Kyanite and Gypsum.
What Are These Carbonate Minerals Used For?
| Mineral | Formation | Uses |
|---|---|---|
| Limestone (calcium carbonate) | Sedimentary rock formed from shells and corals of marine animals and by chemical precipitation in shallow seas; also a rock of the Cuddapah, Vindhyan and Tertiary systems in India | Cement (about one and a half tonnes of limestone per tonne of cement); flux in blast furnaces to remove impurities as slag; lime for construction and sugar refining; soda ash, glass, paper, fertilisers and building stone |
| Dolomite (calcium magnesium carbonate) | Formed when magnesium-rich water changes limestone | Flux in iron and steel; refractory bricks; glass and ceramics; fertiliser and soil conditioner |
| Magnesite (magnesium carbonate) | Formed from the alteration of magnesium-rich rocks and in veins, or by the replacement of dolomite | Refractory bricks that line steel, cement and glass furnaces, magnesium metal, fertiliser, chemicals and medicines |
Limestone is the most widely used of the three, as it supplies two of the basic needs of the economy: cement for infrastructure and housing, and flux for the steel industry, as in Iron and Steel Industry – Process and Location Factors. It is also among the cheapest and bulkiest of minerals, so cement plants are located close to limestone quarries, and the finished cement travels outward by road and rail.
Where Are They Found in India?
| Mineral | Distribution |
|---|---|
| Limestone | Widely distributed: Rajasthan (Chittorgarh, Nagaur, Jaisalmer, Bundi), Madhya Pradesh (Satna, Katni, Rewa, Jabalpur), Andhra Pradesh and Telangana (Kurnool, Guntur, Nalgonda), Gujarat (Kutch, Junagadh, Jamnagar), Karnataka (Gulbarga, Bagalkot), Chhattisgarh (Bilaspur, Raipur), Tamil Nadu (Ariyalur), Himachal Pradesh, Meghalaya and Odisha; the largest reserves are in Karnataka and Andhra Pradesh |
| Dolomite | Chhattisgarh (Bilaspur, Durg), Odisha (Sundargarh), Madhya Pradesh (Jabalpur, Katni), Gujarat (Chhota Udaipur), Karnataka (Shimoga), Andhra Pradesh and Maharashtra; mostly in the Cuddapah and Vindhyan rocks, close to steel plants |
| Magnesite | Uttarakhand (Almora, Pithoragarh, Chamoli), Tamil Nadu (Salem, with the Chalk Hills), Karnataka (Mysuru, Hassan), Rajasthan (Dungarpur, Ajmer) and Kerala; the Salem deposits are the largest in the south and Almora in the Himalaya is the northern centre |
India is the second largest producer of cement in the world, after China, with a capacity of roughly 600 million tonnes a year and a production of around 450 million tonnes, and the main clusters are at Satna in Madhya Pradesh, Chittorgarh and Nagaur in Rajasthan, Chandrapur in Maharashtra, Gulbarga in Karnataka and the Krishna–Godavari region, where limestone is plentiful. The big firms include UltraTech, Adani (Ambuja and ACC), Shree, Dalmia and Ramco.
What Are the Issues?
- Emissions: cement making produces about 7 to 8 per cent of world carbon dioxide, both from the burning of fuel and from the chemical breakdown of limestone, so the industry looks to alternative fuels, blended cement with fly ash and slag, and capture technologies.
- Environment: quarrying causes dust, loss of land and water issues, and in karst areas such as Meghalaya and Himachal it harms landscape and ecology, as in Mining and Quarrying.
- Quality and reserves: good-quality limestone for cement is not evenly spread, and high-grade magnesite is limited, so there is import of magnesia for refractories, mainly from China.
- Link to infrastructure: cement demand follows public infrastructure and housing, so it rises and falls with government spending.
As an analytical point, these bulk, low-value minerals show the principle of location by weight: cement is made where the weight-losing limestone is, while the markets are served by transport. Climate policy will decide their future, because any carbon price or border charge will be felt first by cement and steel, the main users of these minerals.
Why Is This Topic Important?
- Facts States and uses asked
- Industry Cement location
- Climate Cement emissions
What Came Next?
The next topic describes asbestos, kyanite and gypsum. Next topic: Asbestos, Kyanite and Gypsum.
Key People and Terms
- Limestone Calcium carbonate rock
- Dolomite Calcium magnesium carbonate
- Magnesite Magnesium carbonate
- Flux Substance removing impurities as slag
- Refractory Material resisting very high heat
- Clinker Intermediate product of cement
Exam Corner
Points to Remember
- Cement needs limestone as the main raw material.
- Flux removes impurities in blast furnaces.
- Salem and Almora have magnesite.
- India is the second largest cement producer.
- Magnesite is used for refractory bricks.
Do Not Confuse With
- Limestone and dolomite Calcium versus calcium plus magnesium carbonate
- Dolomite and magnesite Mixed carbonate versus magnesium carbonate
- Flux and refractory Impurity remover versus heat-resistant lining
Memory Hook
Limestone for cement, dolomite for flux, magnesite for the furnace lining: three carbonates, three jobs.
Mains Angle
Questions ask for uses, distribution and location of cement. These points add depth.
- Uses Cement, steel, refractory
- Place Spread, with clusters
- Issue Emissions
A Question You May Face
An original practice question, not a past paper question.
“Describe the distribution and uses of limestone in India and discuss why cement plants are located close to limestone quarries.”
How to Answer
- Rocks Three carbonates.
- Uses Cement, flux, lining.
- India States and clusters.
- Issues Emissions, quarrying.
GS Relevance
Frequently Asked Questions
What is limestone used for?
Limestone is used mainly to make cement, which needs about one and a half tonnes of limestone per tonne of cement. It is also used as a flux in blast furnaces of iron and steel plants, to make lime, soda ash and glass, in paper and sugar refining, and as building stone.
Which states have large limestone deposits in India?
Limestone is widely distributed in India. Major states are Rajasthan, Madhya Pradesh, Andhra Pradesh, Telangana, Gujarat, Karnataka, Chhattisgarh and Tamil Nadu. Karnataka and Andhra Pradesh are among those with the largest reserves, and Satna in Madhya Pradesh is a major cement centre.
What is dolomite used for?
Dolomite, a carbonate of calcium and magnesium, is used as a flux in iron and steel production, for refractory bricks, in glass and ceramics, and as a fertiliser and soil conditioner. In India it occurs in Chhattisgarh, Odisha, Madhya Pradesh, Gujarat and Karnataka, often near steel plants.
Where is magnesite found in India?
Magnesite is found in Uttarakhand, at Almora, Pithoragarh and Chamoli, and in Tamil Nadu, at Salem, where the Chalk Hills are well known. It also occurs in Karnataka, Rajasthan and Kerala. It is mainly used for refractory bricks to line steel furnaces.
Why are cement plants located near limestone?
Cement plants are located near limestone quarries because limestone is a bulky raw material, needed in large quantities, and loses weight during processing. Moving it over long distances would be costly, so it is cheaper to make cement at the quarry and transport the finished product.
PYQ Practice — Statement Analysis
1 Limestone is the main raw material for cement.
About 1.5 tonnes per tonne of cement.
2 Magnesite is used to make refractory bricks.
For furnace linings.
3 Salem in Tamil Nadu is known for magnesite.
The Chalk Hills.
4 Dolomite is the principal ore of aluminium.
Bauxite is the ore.
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