metamorphic
Polished lapis lazuli cabochon
Lazurite-rich lapis lazuli; chiefly lazurite (Na₃Ca(Al₃Si₃O₁₂)S), with calcite and pyrite
AI-generated identification · may be incorrectDeep ultramarine-blue, opaque, with rusty-orange/brown matrix or surface inclusions; typically vitreous to greasy luster and no visible cleavage. Mohs hardness is about 5–5.5; lapis is a fine-grained aggregate rather than a single crystal.
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Physical properties
Deep ultramarine-blue, opaque, with rusty-orange/brown matrix or surface inclusions; typically vitreous to greasy luster and no visible cleavage. Mohs hardness is about 5–5.5; lapis is a fine-grained aggregate rather than a single crystal.
Formation & geological history
Forms by contact or regional metamorphism of magnesium- and sulfur-rich carbonate rocks, commonly marble. Major deposits are Precambrian, especially Sar-e-Sang, Afghanistan; smaller sources occur in Chile, Russia, and elsewhere.
Uses & applications
Used for cabochons, beads, carvings, mosaics, and ornamental objects; historically ground as the pigment ultramarine. Commercial value is modest unless the blue is vivid, evenly colored, and relatively free of calcite.
Geological facts
Orange-brown areas may be iron-oxide staining or matrix, while metallic gold flecks—if present—are pyrite, an important quality indicator. The pictured piece appears polished and teardrop-shaped.
Field identification & locations
Identify it by its intense blue color, opaque aggregate texture, moderate hardness, and possible white calcite or brassy pyrite; it should not be confused with blue-dyed howlite or sodalite. Commonly found in metamorphic marble deposits.
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