metamorphic
Lapis Lazuli
Lapis Lazuli (Complex rock primarily composed of Lazurite (Na,Ca)8(AlSiO4)6(S,Cl,SO4,OH)2, Calcite, and Pyrite)
AI-generated identification · may be incorrectHardness: 5 to 5.5 (Mohs); Color: Deep celestial blue; Luster: Vitreous to greasy; Structure: Aggregate; Specific Gravity: 2.7 to 2.9. These beads show a deep uniform blue common in dyed varieties or high-grade specimens.
- Hardness
- 5 to 5
- Color
- Deep celestial blue
- Luster
- Vitreous to greasy
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Physical properties
Hardness: 5 to 5.5 (Mohs); Color: Deep celestial blue; Luster: Vitreous to greasy; Structure: Aggregate; Specific Gravity: 2.7 to 2.9. These beads show a deep uniform blue common in dyed varieties or high-grade specimens.
Formation & geological history
Metamorphic rock formed by contact metamorphism of limestone or marble. The most famous deposits are found in the Sar-i Sang mines of Afghanistan, extracted for over 6,000 years.
Uses & applications
Predominantly used for jewelry (beads, cabochons), ornamental carvings, and historically ground into powder to create ultramarine pigment for fine art.
Geological facts
Lapis lazuli was used in the funeral mask of Tutankhamun and was favored by Cleopatra as eye shadow. The deep blue color is caused by the presence of the trisulfur radical anion in the crystal lattice of lazurite.
Field identification & locations
Identify by its characteristic blue color and often the presence of gold-colored pyrite flecks or white calcite veining. Field identification involves checking for a blue streak and a sulfurous smell when heated or scratched.
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