Also called heliotrope, is a form of Chalcedony, a type of quartz. Bloodstone is green jasper with red inclusions. The red is sometimes caused by iron oxide or red jasper.

Its name originates from its red spots looking like spots of blood. It is used as a seal stone and in signet rings. It is found in Australia, Brazil, China, India and Wyoming, USA. Source: Encyclopedia of gemstones and minerals.