metamorphic
Lapis Lazuli
Lapis Lazuli (Aggregate primarily of Lazurite: (Na,Ca)8(AlSiO4)6(S,SO4,Cl,1-2) with Calcite and Pyrite)
Hardness: 5 to 5.5 on Mohs scale; Color: Deep celestial blue to royal blue with white (Calcite) and gold (Pyrite) inclusions; Luster: Vitreous to greasy; Crystal Structure: Isometric (as Lazurite), though usually found in massive form; Specific Gravity: 2.7 to 2.9.
- Hardness
- 5 to 5
- Luster
- Vitreous to greasy
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Physical properties
Hardness: 5 to 5.5 on Mohs scale; Color: Deep celestial blue to royal blue with white (Calcite) and gold (Pyrite) inclusions; Luster: Vitreous to greasy; Crystal Structure: Isometric (as Lazurite), though usually found in massive form; Specific Gravity: 2.7 to 2.9.
Formation & geological history
Formed by contact metamorphism, where heat and pressure from intruding magma transform limestone or marble into a complex silicate rock. Major deposits have been worked for over 6,000 years in the Sar-e-Sang mines of Afghanistan.
Uses & applications
Used extensively in jewelry (cabochons, beads), decorative carvings, ornate boxes, and historical pigments (ultramarine). It is a highly valued collector's stone and lapidary material.
Geological facts
Lapis lazuli was the source of 'ultramarine,' the most expensive pigment used by Renaissance painters like Vermeer and Michelangelo. It was also highly prized by ancient Egyptians for amulets and the burial mask of Tutankhamun.
Field identification & locations
Identify in the field by its distinct 'ultramarine' blue color, often associated with white Calcite streaks and brassy gold Pyrite specks. Can be found in Afghanistan, Chile, Russia, and Canada. Collectors should look for deep blue saturation and minimal white calcite for higher quality.
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