Lapis Lazuli
Lazurite-rich metamorphic rock · Semi-Precious Gemstone / Decorative Stone
Crystal System
Isometric (for Lazurite component); the material is rock (polymineralic aggregate), typically massive or microcrystalline.
Mineral Group
Silicates (specifically Tectosilicates / Sodalite group)
Chemical Formula
(Na,Ca)8(AlSiO4)6(SO4,S,Cl,OH)2 (Lazurite component), plus Pyrite (FeS2) and Calcite (CaCO3)
Formation Process
Metamorphic; specifically contact metamorphism of limestone or marble subjected to hydrothermal activity.
About This Crystal
An opaque deep-blue rock consisting of various minerals. It shows a vitreous to greasy luster when polished. The specimen displays a characteristic mottled appearance with white Calcite veins and golden-specked inclusions of Pyrite.
Physical Characteristics
Color: Ultramarine to violet-blue; Streak: Light blue; Cleavage: None (rock aggregate); Fracture: Uneven to conchoidal; Specific Gravity: 2.7 to 2.9; Fluorescence: Often exhibits strong orange fluorescence under LWUV due to Calcite or Sodalite content.
Optical Properties
Refractive Index: Approx. 1.50 (weighted average); Birefringence: None (isotropic components); Pleochroism: None; Optical phenomena: None usually, though Pyrite inclusions can provide a metallic gold spark.
Hardness & Durability
Origin Region
Sar-e-Sang, Afghanistan (most famous); Chilean Andes, Russia (Lake Baikal), and Myanmar.
Hardness & Durability
Mohs Hardness: 5 to 5.5. Fairly soft and somewhat porous; prone to scratching and acid attack. Requires careful mounting in jewelry.
Care & Maintenance
Clean only with warm soapy water and a soft cloth; avoid ultrasonic cleaners and steam cleaners. Keep away from acidic household chemicals and prolonged sunlight which may affect dyed specimens.
Rarity & Value
Uncommon; Value is determined by the intensity of the blue color and the absence of excessive white calcite. High-grade 'Afghan' blue with minimal pyrite is most valuable. Often dyed or stabilized with resin.
Special Characteristics
Contains characteristic golden Pyrite inclusions ('fools gold') which distinguish it from Sodalite. High-quality pieces have a uniform, deep 'Royal Blue' color.
Lore & History
Historically used in ancient Mesopotamia, Egypt, and Rome for jewelry and pigments (ultramarine). It was the source of the world's most expensive blue paint. Symbolically associated with the Third Eye chakra, wisdom, and truth.