Which of the following statements is correct?

Question

UnlockIAS · Accepted Answer

Correct — B, Mica is found in Kodarma. Kodarma (also spelt Koderma), in northern Jharkhand — territory that formed part of undivided Bihar until 15 November 2000 — is the centre of the Kodarma–Giridih–Hazaribagh mica belt, the largest muscovite-bearing tract in India and long described as the mica capital of the country. The mica sits in coarse pegmatite veins intruding the Precambrian gneisses and schists of the Chhotanagpur plateau, and that is not an incidental detail: pegmatites are the only rocks that grow mica crystals large enough to be split into sheets, which is why sheet mica is a pegmatite mineral everywhere on Earth and never a sedimentary one. The grade won here is muscovite of such clarity that the trade names it "India ruby mica", and it is the material used as the dielectric in precision capacitors; India has long been the world's leading producer of sheet mica (about 3,500 tonnes in 2010 against Russia's 1,500, on USGS figures).

The Indian Bureau of Mines still records the belt exactly where the option puts it. IBM's Indian Minerals Yearbook 2023, reviewing Jharkhand, lists the state's mica occurrences as "mica in Giridih and Koderma districts" and names no others — two adjoining districts of the same pegmatite tract. The same volume's Bihar review shows what the 2000 bifurcation left behind: Bihar's one recorded mica occurrence is in Nawada district, while the state keeps 94 per cent of India's pyrite resources and has limestone as its only major mineral in production. The trade tables add a caution about what "mica" now means. India exported 1,15,898 tonnes of mica in 2022-23 worth about ₹556 crore, but just 1,433 tonnes of that was block mica; 80,825 tonnes was powder and 12,755 tonnes waste and scrap. Kodarma is still the mica capital of India, but what it ships today is overwhelmingly ground and scrap mica rather than the hand-split sheet that made the name.

There is a second reason to be confident. This is one of the stems on the 69th paper that BPSC lifted almost word for word from a UPSC prelims question. UPSC 2013, General Studies Paper I, Q63 asked candidates to judge three statements — "1. Natural gas occurs in the Gondwana beds. 2. Mica occurs in abundance in Kodarma. 3. Dharwars are famous for petroleum" — and the official UPSC key is (b), 2 only. BPSC has taken the same three ideas, split them into standalone options and shuffled which false pairing appears, but the one surviving true statement is identical, down to the "Kodarma" spelling. An official Government of India key therefore stands behind this answer, even though the 69th CCE has no key of its own.

Why the other options are wrong — (a) The Dharwars are Archaean — the craton formed between about 3.6 and 2.5 billion years ago, built of tonalite–trondhjemite–granodiorite gneisses, greenstone belts and granitoids, and the oldest continental crust in peninsular India. Hydrocarbons need three sedimentary things: an organic-rich source rock, a porous reservoir and an impermeable seal. Crystalline and metamorphosed rock of that age has none of them. What the Dharwars are genuinely famous for is iron ore, manganese and gold, including the Kolar and Hutti fields.  (c) In the rock-system table Indian exams use, diamonds belong with the Vindhyan, not the Cuddapah: the Panna belt of Madhya Pradesh runs about 80 km across the town, and NMDC's Majhgawan mine there is the country's only mechanised diamond mine. Even the Andhra diamonds that gave "Golconda" its name were won from the Banganapalle conglomerate of the Kurnool Group — a younger unit lying unconformably on top of the Cuddapah Supergroup, not within it. The Cuddapah's own reputation rests on limestone, barytes and asbestos. The option tempts because the Cuddapah basin and the Kurnool diamond tract are next-door neighbours in the same corner of Andhra Pradesh — and IBM's own listing makes the trap explicit. Its Indian Minerals Yearbook 2023 groups India's diamond fields into four tracts, the first of which is "the South Indian tract of Andhra Pradesh, comprising parts of Anantapur, Kadapa, Guntur, Krishna, Mahabubnagar and Kurnool districts": Kadapa the district is on the list, the Cuddapah the rock system is not the host. The weight of the resource lies elsewhere anyway. On National Mineral Inventory figures as on 1 April 2020, India's 31.72 million carats of diamond reserves and resources are 90.14 per cent in Madhya Pradesh against 5.74 per cent in Andhra Pradesh and 4.11 per cent in Chhattisgarh, and all 388 carats produced in 2022-23 came from three public-sector mines in Panna.  (d) The Aravallis are a Precambrian folded belt of quartzite, schist, gneiss and marble — crystalline again, and again barren of hydrocarbons. Their wealth is metallic and industrial: the zinc–lead ores of Zawar and Rampura Agucha, the Khetri copper belt, Makrana marble, and mica in the Bhilwara–Ajmer tract. Rajasthan does produce crude oil, which is exactly what makes this option sound plausible, but it comes from the Barmer basin in the far west of the state — a young rift basin filled with Cenozoic sediments that lies beyond the range, not from the hills.

Concept: Indian physical geography sorts the subcontinent's rocks into a handful of "systems", and each carries a standard mineral signature that exams test directly. The Archaean gneisses and schists form the basement. The Dharwar system, roughly 3.6 to 2.5 billion years old and the oldest metamorphosed sedimentaries of the peninsula, is the richest metallic host — iron ore, manganese, gold, copper. The Cuddapah system, Proterozoic sediments resting on the Archaean of Andhra Pradesh, gives limestone, barytes, asbestos and building stone. The Vindhyan system, younger Proterozoic sandstone, shale and limestone, is the diamond-bearing one at Panna and supplied the red sandstone of the Red Fort and Fatehpur Sikri. The Gondwana system, Upper Carboniferous to Jurassic, holds the overwhelming bulk of India's coal. Hydrocarbons belong to none of these: petroleum and natural gas come from Tertiary and Mesozoic sedimentary basins — Mumbai High, Krishna–Godavari, Cauvery, Cambay, Assam–Arakan and Barmer. Mica, finally, is a pegmatite mineral, found in the Precambrian of the Chhotanagpur plateau, the Nellore belt of Andhra Pradesh and the Bhilwara–Ajmer belt of Rajasthan.

State PCS 2023 Q95 — Geography PYQ with Answer

State PCS 2023 Q95 — Geography PYQ with Answer