Banded iron formation (BIF) refers to a rock type, formed by intense metamorphosis of sediments of very ancient age. These sediments were deposited in Pre Cambrian times, around 2 billion years ago, during a phase in the evolution of the earth known as the great oxygen event'. The rough chunk of this picture, actual width 350 mm, shows the fine repetitive bedding of red jasper, dark hematite and goldish tiger-eye that characterizes this rock. This sample is from the iron mining districts of West Australia, the type area where BIF is widespread.