Ruby in Zoisite (Anyolite)

Physical Properties

Hardness: 6-7 (Zoisite base) with 9 (Ruby inclusions); Color: Green zoisite with dark pink/red ruby spots and black pargasite; Luster: Vitreous; Crystal Structure: Orthorhombic (Zoisite) and Hexagonal (Ruby); Specific Gravity: 3.3; Cleavage: One perfect.

Formation & Geological History

Formed through regional metamorphism of magnesium-rich rocks. Most specimens originate from the Proterozoic era and are primarily found in metamorphic belts where pressure and heat allowed the corundum to crystallize within the silicate matrix.

Uses & Applications

Primarily used for decorative carvings, lapidary work, cabochons for jewelry, and as a popular specimen for crystal healing and mineral collections.

Geological Facts

The name 'Anyolite' is derived from the Maasai word 'anyoli', which means green. Unlike many other ruby occurrences, the rubies in this rock are usually opaque and not facet-grade gems.

Field Identification & Locations

Identify in the field by the distinct contrast of red crystals against a green or dark grey-green matrix with black hornblende spots. It is almost exclusively found in the Merelani Hills of Tanzania.

Identified on: 4/29/2026

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