Image: <bdi><a href="https://www.wikidata.org/wiki/Q56247090" class="extiw" title="d:Q56247090"><span title="mineral collector and dealer">Robert M. Lavinsky</span></a></bdi> (CC BY-SA 3.0)
orthorhombicrareSilicates
Tanzanite
Ca₂Al₃(SiO₄)₃(OH)
Tanzanite is a striking blue-violet to violet-blue gemstone, often exhibiting strong pleochroism, appearing different colors from various angles. It typically forms prismatic crystals, sometimes with striations.
Tanzanite Physical Properties
Mohs Hardness
6Crystal System
orthorhombicLuster
vitreousStreak Color
whiteCleavage
perfect on {010}Fracture
uneven to conchoidalSpecific Gravity
3.1Colors
blue, violet, purple, burgundyTransparency
transparentType Locality
Merelani Hills, Arusha Region, TanzaniaMineral Group
SilicatesUses
jewelry, collectorAssociated Minerals
graphite, diopside, tremolite, quartz, calciteRarity
rareGeological Context
Tanzanite forms in regionally metamorphosed graphitic gneisses and schists, often associated with calcium-rich rocks. Its distinctive color is due to the presence of vanadium, which changes oxidation states upon heating.
