How to identify Lapis Lazuli

To correctly identify Lapis Lazuli (Lapis Lazuli), 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. 1

   Color

   Overall color and any zoning or banding

   Intense, uniform deep blue to violet-blue. Often contains golden flecks of pyrite and white streaks or patches of calcite.

2. 2

   Luster

   How the surface reflects light: metallic, vitreous, dull

   Dull to greasy, sometimes vitreous on fresh fracture surfaces.

3. 3

   Texture

   Grain size and surface feel: coarse, fine, glassy

   Fine-grained to medium-grained, granular, often with visible inclusions of pyrite and calcite.

4. 4

   Crystal Form

   Shape of visible crystals or crystal faces

   As a rock, it does not exhibit a single crystal form. The constituent mineral lazurite forms dodecahedral crystals, but these are rarely visible in the massive rock.

5. 5

   Cleavage

   How it breaks: flat cleavage planes vs irregular fracture

   No distinct cleavage as a rock. Lazurite itself has imperfect dodecahedral cleavage, but this is not typically observed in the massive rock.

6. 6

   Geological Environment

   The rock formation and setting where it occurs

   Contact metamorphic zones, particularly in metamorphosed limestones or marbles, often near igneous intrusions.

Key Facts

Hardness

5 to 6 (Mohs scale)

Specific Gravity

2.7 to 2.9 g/cm³

Crystal System

Cubic (for lazurite, the primary mineral component)

Color

Intense blue, violet-blue, greenish-blue

Luster

Dull, greasy, sometimes vitreous

Transparency

Opaque

Fracture

Uneven to conchoidal

Cleavage

None (as a rock); imperfect dodecahedral (for lazurite)

Composition

A rock composed primarily of lazurite, calcite, pyrite, and sodalite.

Physical characteristics

• Crystal Habit: Massive, granular (for the rock); dodecahedral (for individual lazurite crystals, rarely observed)
• Cleavage Type: None (as a rock)
• Fracture Type: Uneven to conchoidal
• Tenacity: Brittle
• Luster Type: Dull to greasy

Explore Lapis Lazuli