Chalcosite: Gemstones Information

The name chalcosite has been given to rocks found in Ambatofinandrahana, Madagascar, which have been used ornamentally.They are composed of reddish brown potassium feldspar, green plagioclase, grey quartz and black mica. The name is unnecessary and incorrectly used in this connection (if it ever is) since it is the validated name for copper sulphide, Cu2S.