mineral
Staurolite
Fe2Al9O6(SiO4)4(O,OH)2
AI-generated identification · may be incorrectHardness of 7 to 7.5 on the Mohs scale, brownish-black to reddish-brown color, subvitreous to resinous luster, and well-known for its distinctive cruciform twinning crystal structure.
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Physical properties
Hardness of 7 to 7.5 on the Mohs scale, brownish-black to reddish-brown color, subvitreous to resinous luster, and well-known for its distinctive cruciform twinning crystal structure.
Formation & geological history
Forms regionally metamorphosed pelitic rocks such as schists and gneisses, typically under intermediate to high-temperature and pressure conditions.
Uses & applications
Widely collected as a mineral specimen and carved or polished into jewelry due to its unique twin crystal formations.
Geological facts
Commonly known as the 'fairy cross' or 'fairy stone' because its 60-degree and 90-degree penetration twins resemble small crucifixes.
Field identification & locations
Easily identified in the field or in schist matrix by its prismatic crystal habit and characteristic cross-shaped twin penetrations.
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Other mineral specimens
Gneiss or Schist
Gneiss or Mica Schist with Garnet
Metamorphic
Limonite
FeO(OH)•nH2O
mineral
Limonite
FeO(OH)•nH2O
mineral
Sandstone (with potential mineral staining/concretions)
Arenite (SiO2 based)
sedimentary
Limonite
FeO(OH)•nH2O
mineral
Tumbled granite
Granite, a coarse-grained felsic intrusive igneous rock
igneous