Bloodstone

Bloodstone forms at shallow depths and low temperatures by precipitation from silica-rich groundwater in fractures and cavities. Most bloodstone used today is mined and cut in India, and the best known material comes from the Deccan Traps of the Kathiawar Peninsula. Other sources include Australia, Brazil, China and Madagascar, and small deposits in California, Nevada, Oregon and Washington in the United States.

Bloodstone is recognized by its dark green body with red spatter, quartz hardness and conchoidal fracture. Green chalcedony with mainly yellow or white spots is usually called plasma, and when colors other than red dominate the material is usually sold as "fancy jasper". Naming varies between references: Gemdat states it is not a jasper even though its texture can look grainy, while Gem-A calls it a jasper. The name "blood stone" has also been applied to hematite, a different mineral, and a glass called "maple stone" has been used as a simulant; glass has a vitreous luster and lower hardness (about 5).

As a chalcedony, bloodstone is tough and needs no special care. Clean it with mild detergent, warm water and a soft brush.

Bloodstone has been a popular gemstone for at least two thousand years and has traditionally been used in men's jewelry, often carved with a signet design and set in rings used to seal documents and letters. European authors, especially in the 18th century and earlier, called it heliotrope, from the Greek for "sun turner". It has been a modern birthstone for March since 1912.

The ancient Greeks apparently believed that bloodstone put into water in sunlight made the water boil. For at least two thousand years many people have believed it can control bleeding and inflammation, and a woodcut of about 1483 shows it being used to stop a nosebleed; geology.com notes there is no scientific or medical evidence for these beliefs. Legend says its red specks formed from the blood of Christ on the Cross, and some scholars have identified it as the twelfth stone of Aaron's breastplate. In India the finest bloodstone is traditionally ground into a powder used as an aphrodisiac.