metamorphic
Lapis lazuli
Lapis lazuli, mainly lazurite (Na₃Ca(Si₃Al₃)O₁₂S) with calcite and pyrite
AI-generated identification · may be incorrectOpaque deep royal-blue stone with white-gray calcite and possible brassy pyrite; Mohs hardness 5–5.5, vitreous to dull luster, granular crystal structure, and no prominent cleavage. The image is consistent with a small rough or tumbled piece, though exact identification requires testing.
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Physical properties
Opaque deep royal-blue stone with white-gray calcite and possible brassy pyrite; Mohs hardness 5–5.5, vitreous to dull luster, granular crystal structure, and no prominent cleavage. The image is consistent with a small rough or tumbled piece, though exact identification requires testing.
Formation & geological history
Formed by contact metamorphism of limestone, typically in Precambrian-aged deposits. Major sources include Afghanistan, Chile, Russia, Pakistan, and Tajikistan.
Uses & applications
Used for beads, carvings, cabochons, inlay, ornaments, and historically ultramarine pigment; rarely used architecturally. Quality depends strongly on saturated blue color, low calcite, and attractive pyrite.
Geological facts
The blue color comes chiefly from sulfur-bearing lazurite; white patches are calcite, while golden flecks are pyrite. It is a rock rather than a single mineral.
Field identification & locations
Identify by its intense blue color, white calcite veining, occasional metallic-gold pyrite, opaque appearance, and moderate hardness; it is softer than quartz and should not scratch glass reliably. Similar blue stones include dyed howlite, sodalite, and azurite.
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