Staurolites can form as twinned crystals at either 60° or 90°, creating interesting natural cruciform pieces. Thus, these stones are popularly called "fairy crosses" or "fairy stones." The name staurolite comes from the Greek word stauros, meaning cross.
They are thought to bring luck to those who hold them.
Staurolite is a reddish brown to black, mostly opaque, nesosilicate mineral with a white streak, it is one of the index minerals that are used to estimate the temperature, depth, and pressure at which a rock undergoes metamorphism.