metamorphic
Lapis Lazuli
Lapis Lazuli (A complex rock primarily composed of Lazurite: (Na,Ca)8(AlSiO4)6(S,Cl,SO4,OH)2)
Hardness: 5 to 5.5 on Mohs scale; Color: Deep celestial blue with golden pyrite inclusions and white calcite streaks; Luster: Dull to vitreous; Crystal Structure: Isometric (lazurite); Cleavage: None/Indistinct; Specific Gravity: 2.7 to 2.9.
- Hardness
- 5 to 5
- Luster
- Dull to vitreous
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Physical properties
Hardness: 5 to 5.5 on Mohs scale; Color: Deep celestial blue with golden pyrite inclusions and white calcite streaks; Luster: Dull to vitreous; Crystal Structure: Isometric (lazurite); Cleavage: None/Indistinct; Specific Gravity: 2.7 to 2.9.
Formation & geological history
Formed through contact metamorphism, typically where limestone or marble is altered by hydrothermal activity. Major deposits are found in the Sar-e-Sang mines in Afghanistan, which have been active for over 6,000 years.
Uses & applications
Primarily used for jewelry (cabochons, beads), decorative carvings, and ornaments. Historically used as a pigment (ultramarine) for Renaissance paintings and cosmetics.
Geological facts
Lapis Lazuli was highly prized by Ancient Egyptians, who used it for the funeral mask of Tutankhamun. It is technically a rock, not a mineral, because it is composed of multiple minerals including lazurite, pyrite, and calcite.
Field identification & locations
Identify in the field by its intense blue color and characteristic metallic gold flecks (pyrite). It is found mostly in Afghanistan, Chile, Russia, and Canada. Collectors look for deep indigo pieces with minimal white calcite and evenly distributed gold pyrite.
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