What’s a mineral?

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My daughter was given a geology kit and has been busily tapping away with her mallet and chisel to release shiny semi-precious gems from large lumps of chalk. But what are minerals like these shiny gems made of, how do they form, and where are they found?

Minerals are solid materials made up of chemical elements. Each type of mineral has a special combination of chemical elements and a particular way of arranging them, some of which make beautiful crystals.

Minerals don’t come from plants or animals or other living things but they are formed naturally (they are not made by humans). Some minerals are formed when volcanoes erupt and hot lava comes out. Lava is a very hot liquid mixture of chemical elements but as it cools down, it forms rocks and minerals. Other types of minerals form when water evaporates from a liquid solution, leaving crystals of salt behind. Because minerals are found inside rocks, people look for them by digging into the Earth’s surface.

So, what about the minerals in my daughter’s geology kit? Let’s find out a bit more about them:

Jasper and carnelian are two forms of a mineral called ‘quartz’. Jasper is usually brown and carnelian is red/orange but they are both made of silicon (Si) and oxygen (O). Their main difference is that jasper is opaque (which means that light can’t travel through it) and carnelian is translucent (which means light can travel through it, so it is see-through).

Hematite is made of iron (Fe), titanium (Ti) and oxygen (O). It is often black or grey and sometimes has red or brown stripes. Pyrite, which is made of iron (Fe) and sulfur (S), is known as ‘Fools Gold’ because its colour looks a bit like gold.

Moonstone is a kind of mineral called ‘feldspar’. It’s white and looks a bit pearly. Moonstone is made of aluminim (Al), silicon (Si) and oxygen (O) mixed with either potassium (K) or with sodium (Na) and calcium (Ca).

Lapis lazuli is mostly made of a mineral called ‘lazurite’, which is made of sodium (Na), calcium (Ca), aluminium (Al), silicon (Si), oxygen (O) and sulfur (S). It is blue but often contains tiny amounts of other minerals, which make it look speckled.

Zircon looks like diamond. It is made of zirconium (Zr), silicon (Si) and oxygen (O). Aquamarine is a pale blue gem from a group of minerals called ‘beryl’. It is made of beryllium (Be), aluminium (Al), silicon (Si) and oxygen (O).

Peridot is yellowy-green in colour. It is made of magnesium (Mg), iron (Fe), silicon (Si) and oxygen (O). Malachite is darker green and is usually stripy. It is made up of copper (Cu), carbon (C), oxygen (O) and hydrogen (H).

If you want to find out more about different types of minerals, check out this list to find out what we use them for!

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