Apatite has hardness of 5 with a color usually in shades of yellow, green or brown, and more rarely colorless, violet or blue. Phosphates in bone and teeth are members of the apatite group. The color in apatite is often due to the presence of rare earth elements or by natural irradiation. The name apatite is from the Greek word to deceive because the gem varieties were often confused with other minerals. Previously apatite was used as a source of phosphate for fertilizer, but today mainly phosphorites are used. Apatites of fine color and transparency are occasionally used as gemstones, however, it is soft mineral, making it suitable only for use as gemstones in earrings, brooches and pendants. The use of apatite gems as ring stones requires extra care to prevent abrasion and loss of polish.