metamorphic
Lapis Lazuli
Lazurite-rich metamorphic rock (approx. Na6Ca2(Al6Si6O24)(S,SO4,Cl)1,2)
Hardness: 5-5.5 on Mohs scale; Color: Deep celestial blue with gold (pyrite) and white (calcite) inclusions; Luster: Dull to vitreous; Crystal Structure: Isometric (for 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 on Mohs scale; Color: Deep celestial blue with gold (pyrite) and white (calcite) inclusions; Luster: Dull to vitreous; Crystal Structure: Isometric (for lazurite component); Cleavage: None/Indistinct; Specific Gravity: 2.7-2.9
Formation & geological history
Formed via contact metamorphism, where heat and pressure from intrusive igneous rocks transform limestone or dolomite into a lazurite-rich rock. Primary deposits are found in ancient metamorphic complexes.
Uses & applications
Used primarily in jewelry (cabochons, beads), decorative carvings, and historically as a pigment (ultramarine) for fine art paints. Also highly valued by mineral collectors.
Geological facts
Lapis lazuli has been mined for over 6,000 years in the Sar-e-Sang mines of Afghanistan. It was used in the funeral mask of Tutankhamun and was the world's most expensive pigment until a synthetic version was created in the 19th century.
Field identification & locations
Identify in the field by its intense 'royal' blue color, lack of transparency, and the presence of brassy pyrite specks. Found mainly in Afghanistan, Russia (Lake Baikal), Chile, and Myanmar. Avoid specimens that look like blue-painted glass or dyed howlite.
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