mineral
Staurolite
Fe2Al9O6(SiO4)4(O,OH)2
AI-generated identification · may be incorrectHardness of 7-7.5 on the Mohs scale, brownish-black to reddish-brown color, subvitreous to resinous luster, and monoclinic crystal system. It is famous for forming distinct cross-shaped penetration twins.
Identified More mineral →
Explore Staurolite in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness of 7-7.5 on the Mohs scale, brownish-black to reddish-brown color, subvitreous to resinous luster, and monoclinic crystal system. It is famous for forming distinct cross-shaped penetration twins.
Formation & geological history
Forms through regional metamorphism of aluminum-rich pelitic rocks like schist and gneiss, typically at medium to high temperatures and pressures.
Uses & applications
Used primarily as a collector's mineral specimen, educational geology tool, and occasionally in abrasive products.
Geological facts
Staurolite is often called the 'fairy cross' or 'fairy stone' due to its natural cruciform twinning, inspiring various local legends and jewelry designs.
Field identification & locations
Easily identified in the field by its characteristic 60-degree and 90-degree cross twins embedded in mica schist. Commonly found in Georgia (USA), Brazil, and Russia.
