metamorphic
Lapis Lazuli
Lapis Lazuli (Complex aggregate including Lazurite: (Na,Ca)8(AlSiO4)6(S,Cl,SO4,OH)2)
Hardness: 5 to 5.5 (Mohs); Color: Deep celestial blue to greenish-blue; Luster: Dull to vitreous/greasy; Crystal Structure: Isometric (for lazurite component); Cleavage: None/Indistinct; Specific Gravity: 2.7 to 2.9
- Hardness
- 5 to 5
- Color
- Deep celestial blue to greenish-blue
- Luster
- Dull to vitreous/greasy
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Physical properties
Hardness: 5 to 5.5 (Mohs); Color: Deep celestial blue to greenish-blue; Luster: Dull to vitreous/greasy; Crystal Structure: Isometric (for lazurite component); Cleavage: None/Indistinct; Specific Gravity: 2.7 to 2.9
Formation & geological history
Formed through contact metamorphism where limestone or marble is altered by hydrothermal processes. Major deposits are found in ancient metamorphic rock formations typically associated with crystalline limestone (marble).
Uses & applications
Used primarily in jewelry, cabochons, carvings, and ornamental objects. Historically ground into powder for the pigment 'ultramarine'. Highly valued by collectors for its vibrant color.
Geological facts
Lapis lazuli has been mined for over 6,000 years, with the SAR-e-Sang mines in Afghanistan being the oldest known source. It was used in the funeral mask of Tutankhamun and was Cleopatra's preferred eye shadow when ground into powder.
Field identification & locations
Identify by its characteristic 'royal blue' color often accompanied by gold-flecked inclusions of pyrite and white streaks of calcite. Primarily found in Afghanistan, Chile, Russia, and Canada. To distinguish from synthetics, look for uneven distribution of pyrite and a cold touch.
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