Chlorite

Chlorite (Gr. chlōros, 'green'), or RIPIDOLITE, an abundant mineral, consisting of silica, alumina, magnesia, and protoxide of iron, in somewhat variable proportions. It is of a green colour, and occurs now and again crystallised in minute hexagonal plates, or in aggregates of small leaflets, either singly or disposed in radial groups, which are scattered over the joint-surfaces of certain rocks, or may occur in a thin incrustation upon other minerals. It is rather soft, and is easily broken or scratched with a knife. Before the blowpipe it is with difficulty fused on thin edges. It is readily distinguished from talc by yielding water in a closed tube. There are several other minerals included with ripidolite under the 'chlorite group' which are with difficulty distinguished from ripidolite and from each other. Chlorite enters largely into the formation of certain schistose rocks (e.g. Chlorite-schist, q.v.), and is common as a decomposition-product after such minerals as mica, augite, hornblende, and garnet.