How to identify Lapis Lazuli
Lapis Lazuli (a rock composed primarily of lazurite, calcite, and pyrite), Opal (hydrated amorphous silica), Turquoise (hydrous phosphate of copper and aluminium), Malachite (copper carbonate hydroxide)
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Open the appTo correctly identify Lapis Lazuli (Lapis Lazuli (a rock composed primarily of lazurite, calcite, and pyrite), Opal (hydrated amorphous silica), Turquoise (hydrous phosphate of copper and aluminium), Malachite (copper carbonate hydroxide)), check each of these features in order. Many rocks and minerals look alike, so cross-reference multiple properties before deciding.
Step-by-step identification
- 1
Color
Overall color and any zoning or banding
Intense azure blue to violet-blue, often with golden flecks of pyrite and white streaks of calcite.
- 2
Luster
How the surface reflects light: metallic, vitreous, dull
Dull to greasy, sometimes vitreous on polished surfaces.
- 3
Texture
Grain size and surface feel: coarse, fine, glassy
Fine-grained to medium-grained, compact.
- 4
Crystal Form
Shape of visible crystals or crystal faces
Massive, granular aggregates. Individual lazurite crystals are rare and typically dodecahedral.
- 5
Cleavage
How it breaks: flat cleavage planes vs irregular fracture
None (as a rock). Lazurite itself has imperfect cleavage on {110}.
- 6
Geological Environment
The rock formation and setting where it occurs
Contact metamorphic zones, particularly in metamorphosed limestones or marbles, often associated with granitic intrusions.
Key Facts
- Hardness
- 5 to 6 on the Mohs scale (due to varying mineral composition).
- Specific Gravity
- 2.7 to 2.9 g/cm³.
- Crystal System
- Isometric (for lazurite, the primary mineral). The rock itself is massive.
- Color
- Intense azure blue to violet-blue.
- Luster
- Dull to greasy.
- Transparency
- Opaque.
- Fracture
- Uneven to conchoidal.
- Cleavage
- None (as a rock).
- Composition
- Rock composed primarily of lazurite (Na,Ca)8[(S,Cl,SO4,OH)2|(Al6Si6O24)], calcite (CaCO3), and pyrite (FeS2).
Physical characteristics
- Crystal Habit: Massive, granular aggregates.
- Cleavage Type: None (as a rock).
- Fracture Type: Uneven to conchoidal.
- Tenacity: Brittle.
- Luster Type: Dull to greasy.
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