AZURITE

A carbonate also known as blue malachite, it is very soft (3-4 on the mohs scale). It contains copper, carbon, oxygen and hydrogen and is a minor source of metallic copper.

It forms when copper deposits are exposed to air and water. Therefore, it is a secondary mineral because it forms when existing minerals are altered. Finest deposits can be found at Brokenhill, Australia and the Atacama desert, Chile.

It was originally used by artists as a blue pigment but it is not stable over time. In humid conditions it transforms into malachite. This is why some ancient famous paintings appear to have a green sky!

PYRITE

Also known as fools gold because it is often mistaken for gold although it has different properties (it is hard and changes form in contact with water). It is one of the most common minerals and forms in great quantities usually in marble and slate. It is poisonous when heated and brittle.

It is a member of the sulphide group and has a cubic crystal system. Twinning may be evident (this is when crystals of the same mineral grow into each other).

Its chemical name is iron sulphide and it is used to make steel and sulphuric acid.