metamorphic
Lapis Lazuli
Complex metamorphic rock primarily composed of Lazurite ((Na,Ca)8(AlSiO4)6(S,Cl,SO4,OH)2), Calcite, and Pyrite
Hardness: 5.0 to 5.5 on Mohs scale; Color: Deep celestial blue to royal blue with white (calcite) and gold (pyrite) inclusions; Luster: Dull to vitreous; Crystal Structure: Isometric (as lazurite); Cleavage: None; Specific Gravity: 2.7 to 2.9
- Hardness
- 5
- Luster
- Dull to vitreous
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Physical properties
Hardness: 5.0 to 5.5 on Mohs scale; Color: Deep celestial blue to royal blue with white (calcite) and gold (pyrite) inclusions; Luster: Dull to vitreous; Crystal Structure: Isometric (as lazurite); Cleavage: None; Specific Gravity: 2.7 to 2.9
Formation & geological history
Formed through contact metamorphism where limestone or dolomite is altered by hydrothermal activity. Major deposits are found in marble. The oldest mines in Afghanistan date back over 6,000 years to the Neogene period.
Uses & applications
Widely used as a gemstone for jewelry (cabochons, beads), decorative carvings, and historically ground into the expensive 'ultramarine' pigment used by Renaissance painters.
Geological facts
In ancient Egypt, it was a favorite stone for amulets and ornaments, including the funeral mask of Tutankhamun. The name is derived from the Latin 'lapis' (stone) and the Persian 'lazhuward' (blue).
Field identification & locations
Identify by its characteristic intense blue color and the presence of brassy metallic pyrite flecks. High-quality specimens have minimal white calcite. Primarily found in Afghanistan (Sar-i Sang), Chile, Russia, and Canada.
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