Q1.
What are rocks made up of?
Answer
Rocks are made up of minerals. A rock is not one single substance — it is a natural mixture of one or more minerals packed together.
| Rock | Where you see it in India | What it is used for |
|---|---|---|
| Granite | Karnataka, Telangana, Rajasthan, Tamil Nadu | Floors, kitchen platforms, temple pillars, monuments |
| Sandstone | Dholpur and Jodhpur (Rajasthan) | Buildings — the Red Fort and Fatehpur Sikri are of red sandstone |
| Marble | Makrana (Rajasthan) | Statues, floors, table tops — the Taj Mahal is of Makrana marble |
| Slate | Kangra (Himachal Pradesh), Markapur (Andhra Pradesh) | Roofing (Fig. 11.6), writing slates, flooring |
| Laterite | Kerala, coastal Karnataka, Goa, Konkan, Odisha | Cut into blocks and used like bricks (Fig. 11.7) |
What we get out of minerals:
- Important metals such as aluminium, gold, copper and iron are extracted from minerals.
- Minerals are used in making aeroplanes, cars, jewellery, cosmetics, and electrical and electronic equipment.
- Even a basic mobile phone contains about a dozen minerals — gold, silver, copper, cobalt and others.
Why they must be used responsibly: it takes thousands to millions of years to form rocks, and minerals are found only in fixed places in fixed amounts. Once dug out and used, no new stock appears — which is exactly why rocks and minerals are non-renewable.
Did you know? Human beings have been making tools from rock for thousands of years — hand axes (Fig. 11.8a) and arrowheads (Fig. 11.8b) of stone have been found at prehistoric sites such as Bhimbetka in Madhya Pradesh.