metamorphic
Lapis lazuli
Lazurite-bearing rock; chiefly lazurite (approximately (Na,Ca)₈(AlSiO₄)₆(S,SO₄,Cl)₂), with calcite and pyrite
AI-generated identification · may be incorrectOpaque, deep blue with scattered pale calcite and possible golden pyrite flecks; vitreous to dull luster, granular texture, Mohs hardness about 5–5.5. This appears to be a cut, polished lapis piece.
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Physical properties
Opaque, deep blue with scattered pale calcite and possible golden pyrite flecks; vitreous to dull luster, granular texture, Mohs hardness about 5–5.5. This appears to be a cut, polished lapis piece.
Formation & geological history
Forms through contact metamorphism of limestone, typically in the presence of sulfur-rich fluids; the famous deposits at Sar-e Sang, Afghanistan, formed in the Hindu Kush during the Precambrian. The specimen’s exact source and age cannot be determined from the image.
Uses & applications
Used for beads, cabochons, carvings, and ornamental objects; historically ground into ultramarine pigment.
Geological facts
High-quality lapis is prized for vivid, relatively even blue color with limited white calcite; pyrite specks are common and can help distinguish it from dyed imitations.
Field identification & locations
Identify by its opaque royal-blue color, granular appearance, and occasional calcite or pyrite inclusions; major sources include Afghanistan, Chile, and Russia. A hand specimen can be checked for natural texture and lack of dye transfer.
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