Non-metallic and rock minerals: mica, limestone and sand

Detail

1. Mica: what it is and why it matters

• Mica is a non-metallic mineral (it has no metal to extract). It is made of plates or leaves that split into very thin, tough and flexible sheets.

• A thousand mica sheets stacked together are only a few centimetres thick.

• Why industry needs it:

• Dielectric strength (how much voltage a material can take before electricity breaks through it) is very high.
• It loses very little power, insulates well (it does not let electricity pass) and resists high voltage.

• → So it is essential in the electrical and electronics industries, for example in capacitors, insulators and heating elements.

• Where it forms: mica occurs in pegmatites (very coarse-grained igneous rocks that form in the last stage of magma cooling). Pegmatites are common in the old crystalline rocks of Peninsular India.

2. Mica: distribution in India

State	Belt / district	Key fact
Jharkhand	Koderma–Gaya–Hazaribagh belt, lower Hazaribagh plateau, on the northern edge of the Chota Nagpur plateau	High-quality belt about 150 km long and 22 km wide. The leading producing belt
Andhra Pradesh	Nellore	Best-quality mica
Rajasthan	Belt of about 320 km from Jaipur to Bhilwara, and around Udaipur	(NCERT Class 10: "around Ajmer")
Others	Telangana, Tamil Nadu, West Bengal (Purulia, Bankura), Madhya Pradesh, Karnataka (Mysuru, Hassan), Kerala (Alappuzha)	Minor producers

• Reserves (current data):
• Total reserves and resources of mica were 6,35,302 tonnes (as on 1 April 2015, UNFC system: United Nations Framework Classification, a standard way of grading how certain a deposit is) [3].
• Of this, 1,14,433 tonnes are "Reserves" and 5,20,869 tonnes are "Remaining Resources" [3].
• Andhra Pradesh leads with 41% of India's mica resources (2015) [3].

• The main mica-bearing pegmatites are in Andhra Pradesh, Bihar, Jharkhand, Maharashtra, Odisha, Rajasthan and Telangana [3].

• Note the trap: Jharkhand's Koderma belt is the best-known producing belt, but Andhra Pradesh holds the largest share of resources.

3. Mica: legal status and problems

• Minor mineral since 2015: the Government of India declared mica a minor mineral in February 2015 [3].
• A minor mineral is one listed by the Centre whose rules and leases are made by state governments.

• So mica producers now report production to the states, not to the Indian Bureau of Mines (IBM) [3].

• Decline of the trade: India once led the world sheet-mica trade. Demand fell as synthetic substitutes replaced natural sheet mica.

• Social problem: illegal collection of scrap mica (small broken pieces) in Koderma (Jharkhand) and Giridih (Jharkhand) has involved child labour (verify current status).

4. Limestone: what it is and its uses

• Limestone is a sedimentary rock (rock formed from layers of material laid down in water and pressed together).
• It is made of calcium carbonate (CaCO₃), or of calcium-magnesium carbonate, which is called dolomite.

• It is found in sedimentary rocks of most geological formations.

• Two main uses:

• Cement: limestone is the basic raw material.
• Flux in the blast furnace: a flux is a substance that removes impurities. In iron smelting, limestone joins with impurities in the iron ore and forms slag, which is removed.
• Other uses: chemicals, fertilisers, paper and sugar refining.

5. Limestone: production and distribution

• Production (2023-24): India produced a record 450 million tonnes of limestone, 10.7% more than 406.5 million tonnes in 2022-23 [2].
• Leading states (state shares):
• Rajasthan is first with 20% of production, followed by Madhya Pradesh (13%) and Andhra Pradesh (2019 and 2020 data) [4][5].
• In 2019, Madhya Pradesh and Andhra Pradesh had 13% each [5].

• (NCERT, Fig. 5.7, 2018-19: Rajasthan, Madhya Pradesh, Andhra Pradesh, Karnataka and Chhattisgarh are the main producers.)

• Link to the cement industry: cement is a heavy, low-value product. So plants are built close to limestone deposits to cut transport costs.

Cement cluster	State	Limestone base
Chittorgarh	Rajasthan	Vindhyan limestone
Satna, Katni	Madhya Pradesh	Vindhyan limestone
Kadapa	Andhra Pradesh	Cuddapah limestone
Gulbarga (Kalaburagi)	Karnataka	Bhima basin limestone

6. Limestone: environmental effects

• Dust and land degradation:
• Grinding limestone for cement, and soapstone for the ceramic industry, produces huge amounts of dust.
• → The dust settles on nearby land.

• → It slows down infiltration (water soaking into the soil), so the land becomes less fertile.

• Cement plants also pollute the air. This is dealt with under resource development and planning.

7. Sand mining

• What sand mining is: taking sand and gravel from riverbeds, floodplains and beaches for concrete, construction and land filling.
• Legal status: sand is a minor mineral under the MMDR Act (Mines and Minerals (Development and Regulation) Act, 1957). So state governments make the rules and give leases.
• Global scale:
• About 50 billion tonnes of sand and gravel are used in the world every year. This makes sand the second most-used resource after water (UNEP, April 2022) [8].
• That is enough to build a wall 27 m wide and 27 m high around the Earth [8].
• UNEP's 2022 report "Sand and Sustainability: 10 Strategic Recommendations to Avert a Crisis" says sand is used faster than nature can replace it, and should be treated as a strategic resource [9][8].

Effects of too much sand mining

• On the river:
• Too much sand is removed → the riverbed gets deeper → the water table (the top level of groundwater) falls → nearby wells dry up.

• The river current changes → riverbanks erode → bridge foundations are exposed and become weak.

• On wildlife:

• Sandbanks are nesting sites. Mining destroys them. Example: gharial and turtle nesting in the Chambal (National Chambal Sanctuary, shared by Rajasthan, Madhya Pradesh and Uttar Pradesh).

• On society: illegal mining feeds "sand mafias" (criminal groups that control illegal extraction and transport), causes revenue loss and leads to violence.

Policy response

• The two MoEFCC guidelines: the Ministry of Environment, Forest and Climate Change issued the Sustainable Sand Mining Management Guidelines 2016 and the Enforcement and Monitoring Guidelines for Sand Mining (EMGSM) 2020 [6].

• Together they regulate sand from finding the deposit to its final use by the buyer [6].

• 2016 Guidelines:

• Each district must prepare a District Survey Report (DSR), which maps where sand is, how much there is and how fast it is replaced.

• Mining needs environmental clearance.

• 2020 Guidelines (EMGSM):

• All sand-carrying vehicles must be registered and fitted with GPS [6][7].
• Weighbridges with CCTV must be set up at stockyards and active mining reaches to record the exact quantity moved [6][7].
• They fix compensation for environmental damage from illegal mining, monitor mining near inter-district and inter-state boundaries, ban mining in certain areas, and set up District Level Task Forces [6][7].

• They provide for aerial surveys, remote sensing and GIS (Geographic Information System: computer mapping of location-based data) to track mining [6][7].

• Alternatives to river sand:

• Manufactured sand (M-sand): sand made by crushing hard rock.
• Recycled construction and demolition waste.
• Offshore sand blocks (covered under offshore minerals).

8. Quick comparison

Feature	Mica	Limestone	Sand
Type	Non-metallic (pegmatite)	Rock mineral (sedimentary)	Rock mineral (loose sediment)
Legal status	Minor mineral (since 2015) [3]	Major mineral (cement grade)	Minor mineral
Leading area	Koderma–Gaya–Hazaribagh (Jharkhand); Andhra Pradesh has most resources	Rajasthan (20%) [4]	Riverbeds across India
Main use	Electrical insulation	Cement, flux	Concrete, construction
Main concern	Child labour, falling demand	Dust, land degradation	Riverbed lowering, mafias

Prelims Hooks

• Koderma–Gaya–Hazaribagh belt (Jharkhand/Bihar) is the leading mica-producing belt. It is about 150 km × 22 km, in the lower Hazaribagh plateau.
• Nellore (Andhra Pradesh) gives the best-quality mica. Andhra Pradesh also has the largest share of mica resources (41%, 2015) [3].
• Rajasthan's mica belt runs about 320 km from Jaipur to Bhilwara.
• Mica was made a minor mineral in February 2015 [3]. River sand is also a minor mineral, so states regulate both.
• Mica's use comes from its high dielectric strength and insulation, not from conducting electricity. This is a common trap.
• Limestone is calcium carbonate. Dolomite is calcium-magnesium carbonate. Both are used as a flux in the blast furnace.
• Rajasthan is the top limestone-producing state (about 20%), followed by Madhya Pradesh [4][5]. India's limestone output was 450 million tonnes in 2023-24 [2].
• Cement cluster–state pairs: Chittorgarh–Rajasthan; Satna, Katni–Madhya Pradesh; Kadapa–Andhra Pradesh; Gulbarga–Karnataka.
• Sand guidelines in order: Sustainable Sand Mining Management Guidelines 2016 → Enforcement and Monitoring Guidelines 2020, both from MoEFCC [6].
• Sand and gravel are the world's second most-used resource after water, at about 50 billion tonnes a year (UNEP 2022) [8].

Mains Points

• Where the industry locates (GS-I): cement is a heavy, low-value product, so plants are built on limestone deposits. This explains the Vindhyan clusters (Chittorgarh, Satna, Katni) and the Cuddapah cluster (Kadapa). Mica, by contrast, comes from Peninsular pegmatites (Chota Nagpur, Nellore, Aravalli), which shows how geology decides where minerals are found.
• Mica's decline: synthetic substitutes cut demand for sheet mica. Mica was also made a minor mineral in 2015 [3], so control passed to the states. Weak regulation then allowed informal scrap collection and child labour in Koderma and Giridih. Answers should suggest legal value chains, traceability and better livelihoods.
• Sand mining as a resource crisis (GS-III): it lowers riverbeds and water tables, erodes banks, weakens bridges and destroys nesting habitat (gharial and turtles in the Chambal). The response so far: DSRs and environmental clearance (2016), and GPS, CCTV weighbridges, remote sensing and district task forces (2020) [6][7]. Enforcement is still weak because states control sand and sand mafias are powerful.
• The way forward: treat sand as a strategic resource, in line with UNEP's 2022 report [9]. Promote M-sand and recycled construction waste, explore offshore sand blocks, use satellite monitoring, and make dust control compulsory in limestone grinding units to stop land degradation.