Miners also call calcite calcspar.

Calcite consists of the elements
calcium, carbon and oxygen.

The chemical formula is CaCO₃.

The crystals of calcite look colourless.
However, this rarely occurs in nature.
Tiny quantities of other elements colour the crystals
in all the colours of the rainbow: white, grey, yellow,
pink, red, blue, green, brown and even black.

Calcites can form hundreds of different crystal shapes. 
They are true shape magicians.

Double spar is particularly impressive. 
It is transparent, clear and has the shape of a rhombohedron. 
If you look through it, you can see everything twice!

The scalenohedron is also a special crystal shape 
that is somewhat reminiscent of a  jelly bag cap.

On the Mohs hardness scale, calcite has a hardness of 3.
This means that it is a little harder
than your fingernail.
So you can't scratch it.

On the Mohs scale of hardness, diamond
is the hardest mineral in the world with a hardness of 10.
Tallow, on the other hand, is very soft and has a hardness of 1.

If you hit a piece of calcite with a hammer,
straight and smooth cleavage pieces are produced.
This is a typical sign of good cleavage.
Sometimes you can recognise such fissures in the crystal.
They look like cracks in the glass.

Calcite is a continuous mineral.
This means that it is very common and
occurs all over the world.

You will often find it together with the minerals
Quartz, fluorite (fluorspar), barite (barite),
galena (galena), sphalerite (zinc blende)
or pyrite (fool's gold).

Calcite is also a component of rocks such as marble or limestone.

Calcite is a very important raw material because
it is needed in the production of gypsum and cement.

Fertilisers can also be made from calcite.

The effect of birefringence
is particularly important for lenses.
This can be used to build polarisation microscopes 
in order to examine the composition of rocks even more closely.