Fuchsite mineral sample. This is a phyllosilicate mineral that in addition to the silicate components, contains the elements potassium, chromium and aluminium. Flakes of green crystals are seen here. It is the presence of the chromium that produces this green colour, and distinguishes this mineral from the similar muscovite, of which it is a variety. This sample, from Minas Gerais in Brazil, is 6.5 centimetres across.