Ferro-axinite
Image: Didier Descouens (CC BY 3.0)
Mineral NameFerro-axinite
Chemical FormulaCa2FeAl2BSi4O15(OH)
Mohs Hardness6.5
Crystal Systemtriclinic
Lustervitreous
Streak Colorwhite
CleavageGood on {100}, distinct on {001}, poor on {110}
Fractureconchoidal to uneven
Specific Gravity3.3
Colorsviolet-brown, purplish-brown, brown
Transparencytranslucent
Type LocalityL'Arbizon, Saint-Lary, Hautes-Pyrénées, Midi-Pyrénées, France
Mineral GroupBorosilicates
Usescollector's specimens, gemstone (rarely)
Associated Mineralsquartz, epidote, actinolite, calcite, prehnite, datolite
Rarityuncommon
Description
A large, tabular, purplish-brown Ferro-axinite crystal, approximately 2cm in size, displaying a vitreous luster and embedded within a light-colored, granular matrix.
Geological Context
Ferro-axinite typically forms in contact metamorphic environments, particularly in granitic intrusions into carbonate-rich rocks, or in veins within metamorphic terrains.
