Malachite

A polished sample of malachite showing off its color and patterns.

Malachite is a mineral known for its green colour. It is the mineral form of basic copper carbonate, with the chemical formula Cu₂CO₃(OH)₂. Malachite has been used as a pigment, for construction and decoration, and as an ore of copper.

It is related to azurite, another colourful copper carbonate ore. It also looks very similar to annabergite, which is a nickel ore. Miners confusing malachite and annabergite is what led to the discovery and name of nickel.