Axinite
Image: Didier Descouens (CC BY 3.0)
Mineral NameAxinite
Chemical FormulaCa2FeAl2BSi4O15(OH)
Mohs Hardness6.5
Crystal Systemtriclinic
Lustervitreous
Streak Colorwhite
CleavageDistinct to good in one direction ({100})
Fractureconchoidal
Specific Gravity3.3
Colorsbrown, violet, yellow, gray, green
Transparencytransparent to translucent
Type LocalitySt Christophe-en-Oisans, Isère, France
Mineral GroupBorosilicates
Usescollector's specimens, gemstone (rarely)
Associated Mineralsquartz, epidote, prehnite, actinolite, calcite, tourmaline
Rarityuncommon
Description
A well-formed, brownish-violet Axinite crystal exhibiting characteristic wedge-shaped habit, approximately 6 cm in view, set against a dark background.
Geological Context
Axinite typically forms in contact metamorphic environments, often in metasomatized limestones or granitic intrusions, and can also be found in veins and cavities within granitic rocks.
