What minerals are and where they occur

Minerals are everywhere. From a tiny pin to a tall building or a big ship, almost everything we use is made from minerals: railway lines, roads, machines, cars, buses and aeroplanes. Your toothpaste is full of them: silica and limestone scrub the teeth, fluoride (from the mineral fluorite) fights cavities, titanium oxide makes it white, and mica makes it sparkle. Even our food has minerals: only about 0.3 per cent of what we eat, but without them our body could not use the other 99.7 per cent.

Haban's question. Haban comes from a remote village to Guwahati and sees 'houses' moving on the road. His father explains: these are buses and trains, made of metals like iron and aluminium, and they move because an engine uses energy. Metals and energy both come from the earth.

What is a mineral? Geologists call it a 'homogenous, naturally occurring substance with a definable internal structure'. Homogenous means it is the same all through, like a roti, not like a pizza with different toppings in different places. Some are very hard, like diamond; some are very soft, like talc. Rocks are made of minerals: limestone has just one, most rocks have several. Over 2000 minerals are known.

What is an ore? An ore is a mass of a mineral mixed with other things, with enough of the mineral to make digging it out profitable. Simple test: can you take the metal out and still make money? Then it is an ore. Whether a deposit becomes a mine depends on how rich the ore is, how easy it is to dig, and how close it is to the market.

Rat-hole mining. Most minerals in India belong to the nation and need government permission to mine. But in many tribal areas of the north-east, minerals belong to individuals or communities. In Meghalaya (Jowai and Cherrapunjee), families dug coal through long, narrow tunnels: 'rat-hole' mining, which is dangerous (roofs fall, water floods in). The National Green Tribunal has declared it illegal.