How to identify Anthracite

To correctly identify Anthracite (Anthracite), 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

   Jet black to dark gray.

2. 2

   Luster

   How the surface reflects light: metallic, vitreous, dull

   Bright, submetallic to metallic, often vitreous (glassy).

3. 3

   Texture

   Grain size and surface feel: coarse, fine, glassy

   Smooth, hard, and brittle. Often exhibits conchoidal fracture.

4. 4

   Crystal Form

   Shape of visible crystals or crystal faces

   Amorphous (non-crystalline) or cryptocrystalline, though it is a rock, not a mineral in the strict sense. It does not form distinct crystals.

5. 5

   Cleavage

   How it breaks: flat cleavage planes vs irregular fracture

   No true cleavage; exhibits conchoidal fracture.

6. 6

   Geological Environment

   The rock formation and setting where it occurs

   Typically found in highly folded and faulted sedimentary basins that have undergone significant tectonic compression and burial, leading to high-grade metamorphism of pre-existing lower-rank coals. Common in foreland basins adjacent to orogenic belts.

Key Facts

Hardness

2.5-2.75 on Mohs scale (relatively soft, but harder than lower-rank coals)

Specific Gravity

1.3-1.7 g/cm³ (denser than lower-rank coals)

Crystal System

Amorphous (non-crystalline)

Color

Jet black, sometimes with a slight brownish tint

Luster

Submetallic to metallic, vitreous

Transparency

Opaque

Fracture

Conchoidal (shell-like, curved surfaces), brittle

Cleavage

None (no true cleavage)

Composition

Primarily carbon (92-98% fixed carbon), with minor amounts of volatile matter, moisture, and ash.

Physical characteristics

• Crystal Habit: Massive, amorphous; does not form distinct crystals.
• Cleavage Type: None
• Fracture Type: Conchoidal, brittle
• Tenacity: Brittle
• Luster Type: Submetallic to metallic, vitreous

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