metamorphic
Lapis Lazuli
Sodalite-rich metamorphic rock containing Lazurite (Na,Ca)8(AlSiO4)6(S,Cl,SO4,OH)2
Hardness: 5-5.5 (Mohs scale); Color: Deep blue with white calcite specks and gold-flecked pyrite inclusions; Luster: Dull to vitreous; Crystal structure: Isometric (Lazurite component); Cleavage: None/Indistinct; Specific gravity: 2.7-2.9
- Hardness
- 5-5
- Luster
- Dull to vitreous
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Physical properties
Hardness: 5-5.5 (Mohs scale); Color: Deep blue with white calcite specks and gold-flecked pyrite inclusions; Luster: Dull to vitreous; Crystal structure: Isometric (Lazurite component); Cleavage: None/Indistinct; Specific gravity: 2.7-2.9
Formation & geological history
Formed via contact metamorphism, where limestone or marble is altered by hydrothermal processes. Major deposits date back over 6,000 years, particularly in the Sar-e-Sang mines of Afghanistan.
Uses & applications
Used primarily in jewelry as cabochons or beads, ornamental carvings, and historically ground into the expensive pigment 'ultramarine' for fine art painting.
Geological facts
Lapis Lazuli was the source of the most expensive pigment of the Renaissance, used by Michelangelo and Vermeer. It is technically an aggregate of several minerals (Lazurite, Calcite, Pyrite, and Sodalite) rather than a single mineral.
Field identification & locations
Identify by its characteristic ultramarine color and 'night sky' appearance created by gold-colored pyrite flecks. High-quality specimens have minimal white calcite. Primarily found in Afghanistan, Chile, Russia, and Canada.
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