αἱμάτιτης

Bloodstone is a variety of chalcedony — dark green jasper speckled with spots of iron oxide that look like drops of blood. The Greeks called it haimatítēs, from haima, blood. Pliny the Elder described it in his Natural History around 77 CE, noting that it was believed to staunch hemorrhages when applied to wounds. The stone's reputation was medical before it was decorative.

Medieval Christians reinterpreted the stone entirely. A legend arose that bloodstone was formed at the Crucifixion, when drops of Christ's blood fell onto green jasper at the foot of the cross. This story has no ancient source, but it proved durable. By the 1200s, bloodstone was being carved into scenes of the Crucifixion and set into church reliquaries. The medical stone became a devotional one.

In Renaissance Europe, bloodstone was called heliotrope — from the Greek helios (sun) and trepein (to turn). This name came from Pliny's separate claim that the stone could turn the sun red when placed in water. Two names, two different superstitions, one stone. Signet rings carved from bloodstone were common among European aristocracy because the stone's hardness held a clean impression in sealing wax.

Bloodstone is still the traditional birthstone for March. It remains one of the few gemstones named entirely for what people believed it could do rather than for what it looks like. The iron oxide spots are rust. The green is silica. The name remembers neither chemistry.