Lapis Lazuli
Lazurite-rich Metamorphic Rock · Semi-Precious Gemstone / Metamorphic Rock
Crystal System
Cubic (Isometric) for the constituent mineral lazurite, though the rock itself is typically found in massive, non-crystalline forms.
Mineral Group
Sodalite group (Subgroup of Tectosilicates)
Chemical Formula
Main component Lazurite: (Na,Ca)8(AlSiO4)6(SO4,S,Cl,OH)2, typically with associated Pyrite (FeS2) and Calcite (CaCO3).
Formation Process
Metamorphic; typically forms as a result of contact metamorphism where limestone or dolomite is transformed by heat and chemical changes near igneous intrusions.
About This Crystal
An opaque, deep blue rock featuring white streaks of Calcite and golden-colored specks of Pyrite. It has a dull to vitreous luster and a rich ultramarine body color.
Physical Characteristics
Color: Deep blue to violet-blue; Streak: Light blue; Cleavage: None (in rock form); Fracture: Uneven to conchoidal; Specific Gravity: 2.7–2.9; Fluorescence: Calcite inclusions may glow pink/orange under LWUV.
Optical Properties
Opaque; Refractive Index: approximately 1.50 (aggregate); lacks birefringence or pleochroism due to its aggregate nature.
Hardness & Durability
Origin Region
Sar-e-Sang, Badakhshan Province, Afghanistan (primary historical source); also Chile, Russia, and Lake Baikal.
Hardness & Durability
Mohs Hardness: 5.0 to 5.5; Fair toughness, but sensitive to pressure and high heat. Moderate wearability for jewelry.
Care & Maintenance
Avoid chemicals, acids, and ultrasonic cleaners. Clean with warm, soapy water and a soft cloth only. Store separately from harder stones like quartz to prevent scratching.
Rarity & Value
Common to Uncommon; value is dictated by the intensity of 'royal blue' color and the balance of pyrite (valued) versus calcite (less valued). Common treatments include dyeing or resin impregnation to enhance color.
Special Characteristics
Characteristic golden specks of Pyrite inclusions and white veins of Calcite; 'Ultramarine' pigment is historically derived from this mineral.
Lore & History
Used since the 7th millennium BCE; prized by Ancient Egyptians for amulets (e.g., King Tutankhamun's mask) and used by Renaissance artists for ultramarine pigment. Historically associated with wisdom, truth, and the throat chakra.