Lapis Lazuli
Lazurite-rich metamorphic rock (not a single mineral) · Semi-Precious Gemstone / Decorative Stone
Crystal System
Cubic (for the lazurite component), but typically occurs as massive aggregate without visible external crystal forms.
Mineral Group
Silicates (specifically Tectosilicates of the Sodalite group)
Chemical Formula
(Na,Ca)8(AlSiO4)6(S,Cl,SO4,OH)2 (Lazurite) with inclusions of Pyrite (FeS2) and Calcite (CaCO3)
Formation Process
Metamorphic (Contact Metamorphism); specifically formed through the alteration of limestone or marble by hydrothermal or contact process.
About This Crystal
An opaque rock featuring an intense deep blue color (ultramarine). The specimen shows a vitreous to greasy luster when polished. It typically displays a mottled or 'denim' appearance with white streaks of Calcite and golden specks of Iron Pyrite.
Physical Characteristics
Color: Ultramarine blue; Streak: Light blue; Cleavage: None (massive); Fracture: Uneven to conchoidal; Specific Gravity: 2.7–2.9; Fluorescence: Often shows orange/pink patches (calcite) under LWUV.
Optical Properties
Refractive Index: Approximately 1.50 (aggregate); Singly refractive; No pleochroism or dispersion; Opaque transparency.
Hardness & Durability
Origin Region
Sar-e-Sang, Afghanistan (most famous source); Chile, Russia (Lake Baikal), Myanmar, and Canada.
Hardness & Durability
Mohs Hardness: 5 to 5.5; Fair toughness; Sensitive to high pressure, high heat, and household acids.
Care & Maintenance
Clean with warm soapy water only; avoid ultrasonic and steam cleaners. Store away from harder gems like quartz or diamonds to prevent scratching. Avoid acidic chemicals.
Rarity & Value
Uncommon; Value depends on the intensity of blue, the presence of pyrite (desirable in moderation), and the absence of calcite (white patches). High-grade Afghan lapis is most valued.
Special Characteristics
The presence of golden Pyrite inclusions serves as a 'signature' for natural Lapis Lazuli versus synthetic imitations or blue sodalite.
Lore & History
Used for over 6,000 years; highly prized by Ancient Egyptians for amulets (e.g., King Tut's mask) and ground into 'ultramarine' pigment for Renaissance painters. Spiritually associated with the Third Eye chakra, truth, and wisdom.