Andradite
Image: Didier Descouens (CC BY-SA 4.0)
Mineral NameAndradite
Chemical FormulaCa3Fe2(SiO4)3
Mohs Hardness6.5
Crystal Systemcubic
Lustervitreous
Streak Colorwhite
Cleavagenone
Fractureconchoidal to uneven
Specific Gravity3.85
Colorsdark brown, yellowish-brown, greenish-brown
Transparencytranslucent
Type LocalitySibinndi, Nioro du Sahel Circle, Kayes Region, Mali
Mineral GroupSilicates
Usesjewelry, abrasive, collector
Associated Mineralsepidote, chlorite, calcite, quartz, magnetite
Rarityuncommon
Description
A single, well-formed, dark brownish-green to yellowish-brown andradite crystal, approximately 4.2 cm in size, exhibiting a distinct dodecahedral or trapezohedral habit with a somewhat rough surface texture.
Geological Context
Andradite typically forms in contact metamorphic rocks, particularly skarns, where iron-rich fluids interact with calcium-rich sedimentary rocks like limestones or dolomites.
