Tanzanite
Image: Didier Descouens (CC BY 3.0)
Mineral NameTanzanite
Chemical FormulaCa₂Al₃(SiO₄)(Si₂O₇)O(OH)
Mohs Hardness6
Crystal Systemorthorhombic
Lustervitreous
Streak Colorwhite
Cleavageperfect on {010}
Fractureuneven to conchoidal
Specific Gravity3.35
Colorsblue, violet, purplish-blue
Transparencytransparent
Type LocalityMerelani Hills (Mererani), Lelatema Mts, Arusha, Tanzania
Mineral GroupSilicates
Usesjewelry, collector
Associated Mineralsgraphite, diopside, tremolite, quartz, calcite
Rarityrare
Description
This is a faceted oval-cut gemstone displaying a vibrant blue-violet color, characteristic of tanzanite, with multiple reflective facets.
Geological Context
Tanzanite forms in regionally metamorphosed rocks, specifically in graphitic gneisses and schists, often associated with hydrothermal alteration and metasomatism in a unique geological setting.
