Lapis Lazuli
Lapis Lazuli (a rock primarily composed of Lazurite, Calcite, and Pyrite) · Semi-Precious Gemstone / Decorative Stone
Crystal System
Isometric (as Lazurite crystals); typically occurs in a massive, fine-grained, or compact habit.
Mineral Group
Silicates (specifically Tectosilicates of the Sodalite group)
Chemical Formula
(Na,Ca)8(AlSiO4)6(S,Cl,SO4,OH)2 (Lazurite) with FeS2 (Pyrite) and CaCO3 (Calcite)
Formation Process
Metamorphic; typically forms through contact metamorphism within crystalline limestones (marbles).
About This Crystal
An opaque, deep blue rock with a vitreous to greasy luster. It features golden metallic specks of pyrite and white or greyish streaks of calcite. The texture is usually fine-grained and dense.
Physical Characteristics
Color: Ultramarine to violet-blue; Streak: Light blue; Cleavage: None (rock); Fracture: Conchoidal to uneven; Specific Gravity: 2.7–2.9; Fluorescence: Often shows weak orange or pink spots under LWUV due to calcite.
Optical Properties
Refractive Index: Approx. 1.50 (aggregate); Birefringence: None (singly refractive); Lacks pleochroism due to its aggregate nature; exhibits no fire or dispersion.
Hardness & Durability
Origin Region
Sar-e-Sang, Afghanistan (primary historical source); also Chile, Russia, Myanmar, and the USA.
Hardness & Durability
Mohs hardness: 5.0 to 5.5; Toughness: Fair to poor due to porous nature; Stability: Sensitive to high heat, acids, and household chemicals.
Care & Maintenance
Clean only with warm, soapy water; avoid ultrasonic and steam cleaners. Store away from harder gems like quartz or sapphire to prevent scratching. Protect from prolonged sunlight to prevent fading.
Rarity & Value
Uncommon; Value is determined by the intensity of the blue color and the absence of eye-visible calcite; 'Royal Blue' from Afghanistan is most prized.
Special Characteristics
Characterized by the distinctive 'starry night' appearance created by golden pyrite inclusions against a deep blue lazurite background.
Lore & History
Historically used in the funeral mask of Tutankhamun and ground into 'ultramarine' pigment for Renaissance paintings. Symbolizes wisdom and truth; traditionally associated with the Third Eye chakra.