ANDRADITE VAR. DEMANTOID

Sitting in a bed of skarn, deep green opaque demantoid garnets are superbly contrasted in the matrix. The way that the largest crystal sits atop makes this a great display piece, and it gorgeously displays the refractivity that demantoid garnets are known for. Simply an exemplary sample of this species.

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Demantoid garnet from Belqeys Mountain, Iran, occurs within serpentinized ultramafic host rocks. The garnets form through metasomatic processes involving hydrothermal fluids rich in calcium, iron, and silica interacting with serpentinite. These fluids circulate through fractures in the host rock at temperatures between 300-400°C. The resulting demantoid crystals display characteristic dodecahedral morphology and range from <1mm to 2cm in size. They frequently exhibit distinctive "horsetail" inclusions of chrysotile fibers, a characteristic feature of serpentinite-hosted demantoid deposits. The garnets typically show high chromium content, contributing to their distinctive bright green coloration. This deposit represents a typical example of low- to medium-temperature hydrothermal mineralization within an ophiolitic complex.