M487 - Staurolite crystals in a matrix rock of schist. From Russia. Basic silicate of iron and aluminum, often with magnesium and zinc. Hardness 7 to 7-1/2 on the Mohs hardness scale. Commonly called "Fairy Cross" or "Fairy Stones". Monoclinic crystals in twins, intergrown at nearly 60 degrees. The right-angled staurolite crystals with penetration twins are popular as good luck charms. From Russia.

Staurolite is a nesosilicate mineral that is a red brown to black color, mostly opaque. The name is derived from the Green, "stauros" for cross and "lithos" for stone in reference to the common twinning.

Staurolite is a regional metamorphic mineral of intermediate to high grade. It occurs with almandine garnet, micas, kyanite; as well as albite, biotite, and sillimanite in gneiss and schist of regional metamorphic rocks. It is the official state mineral of the state of Georgia, USA. It is also found in Fairy Stone State Park in Patrick County, Virginia. The park is named for a local name of staurolite from a legend in the area.

Staurolite is one of the index minerals that are used to estimate the temperature, depth, and pressure at which a rock undergoes metamorphism.

From Russia.