How to identify Silicon Carbide

To correctly identify Silicon Carbide (Silicon Carbide (SiC)), 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

   Natural moissanite is typically colorless, pale green, or greenish-black. Synthetic SiC can be colorless, green, blue, or black, often with iridescent hues.

2. 2

   Luster

   How the surface reflects light: metallic, vitreous, dull

   Adamantine to metallic, often with a sub-metallic sheen in synthetic forms.

3. 3

   Texture

   Grain size and surface feel: coarse, fine, glassy

   Crystalline, often with sharp edges in synthetic forms. Natural moissanite forms small, often hexagonal, crystals.

4. 4

   Crystal Form

   Shape of visible crystals or crystal faces

   Hexagonal (alpha-SiC, 6H-SiC, 4H-SiC) or cubic (beta-SiC, 3C-SiC). Natural moissanite typically forms small, platy hexagonal crystals.

5. 5

   Cleavage

   How it breaks: flat cleavage planes vs irregular fracture

   Poor to distinct on {0001} in hexagonal polytypes.

6. 6

   Geological Environment

   The rock formation and setting where it occurs

   Natural moissanite is found in kimberlites, lamproites, and as inclusions in some meteorites. These environments are characterized by high-pressure, high-temperature conditions deep within the Earth's mantle or extraterrestrial origins.

Key Facts

Hardness

9-9.5 (Mohs scale)

Specific Gravity

3.21 g/cm³

Crystal System

Hexagonal (most common polytypes, e.g., 6H-SiC, 4H-SiC) or Cubic (3C-SiC)

Color

Colorless, pale green, greenish-black (natural); colorless, green, blue, black (synthetic)

Luster

Adamantine to metallic

Transparency

Transparent to opaque

Fracture

Conchoidal to uneven

Cleavage

Poor to distinct on {0001}

Composition

Silicon Carbide (SiC)

Physical characteristics

• Crystal Habit: Natural: Small, platy hexagonal crystals. Synthetic: Hexagonal plates, blocky crystals, or granular aggregates.
• Cleavage Type: Poor to distinct basal cleavage in hexagonal polytypes.
• Fracture Type: Conchoidal to uneven, very brittle.
• Tenacity: Brittle
• Luster Type: Adamantine to metallic

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