mineral

Rough Tanzanite

Zoisite (Ca2Al3(SiO4)3(OH))

AI-generated identification · may be incorrect

Hardness: 6-7 Mohs; Color: Purplish-blue to violet; Luster: Vitreous; Crystal Structure: Orthorhombic; Cleavage: Perfect one direction; Specific Gravity: 3.35

Hardness: 6-7 Mohs
Color: Purplish-blue to violet
Luster: Vitreous

Identified April 12, 2026More mineral →

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Physical properties

Hardness: 6-7 Mohs; Color: Purplish-blue to violet; Luster: Vitreous; Crystal Structure: Orthorhombic; Cleavage: Perfect one direction; Specific Gravity: 3.35

Formation & geological history

Formed through regional metamorphism in the Merelani Hills of Tanzania approx. 585 million years ago. It occurs in boudins within graphitic schists.

Uses & applications

Primarily used as a gemstone in high-end jewelry and as a rare investment-grade mineral specimen for collectors.

Geological facts

Tanzanite is a 'one-source' gemstone, found only in a small area (4km long) in Northern Tanzania. It was named by Tiffany & Co. in 1968 and is famous for its trichroism.

Field identification & locations

Identify by its distinctive pleochroism (appearing blue, violet, or burgundy from different angles) and its location-specific occurrence. In the field, look for hexagonal prismatic crystals within metamorphic host rock.