Tigers eyeTigers eye
is formed when quatrz replaces crocidolite, and takes on the fibrous structure of the crocidolite. It is occasionally called petrified crocidolite. The fibrious structure of the quartz
gives rise to a shimmering colour change effect where the shade of the rock depends on the angle it is viewed at. The most common colour is a yellow/brown, and is also found in blue.