metamorphic
Anthracite Coal
Anthracite (Carbon-rich metamorphic coal)
Hardness: 2.5–3.0 on Mohs scale; Color: Black to steel-grey; Luster: Submetallic, shiny, and vitreous; Structure: Amorphous (non-crystalline); Fracture: Conchoidal; Specific Gravity: 1.3–1.8.
- Hardness
- 2
- Color
- Black to steel-grey
- Luster
- Submetallic, shiny, and vitreous
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Physical properties
Hardness: 2.5–3.0 on Mohs scale; Color: Black to steel-grey; Luster: Submetallic, shiny, and vitreous; Structure: Amorphous (non-crystalline); Fracture: Conchoidal; Specific Gravity: 1.3–1.8.
Formation & geological history
Formed through the regional metamorphism of sedimentary coal (bituminous) under intense pressure and heat. This process typically occurs during mountain-building events (orogenies) and takes millions of years, often dating back to the Carboniferous period.
Uses & applications
Primarily used as a residential and industrial fuel due to its high carbon content and low smoke emission. Also used in water filtration systems and for carving decorative ornaments and jewelry (jet-like items).
Geological facts
Anthracite is the highest grade of coal, containing 86%-97% carbon. Unlike softer coals, it is relatively clean to the touch and burns with a short blue flame and very little smoke.
Field identification & locations
Identify in the field by its distinct shiny, 'glassy' black luster and its light weight relative to stone. It will not smudge fingers easily like bituminous coal. Common in the Appalachian region of Pennsylvania, USA, and parts of Wales and China.
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