metamorphic
Anthracite Coal
Anthracite
Hardness: 2.5-3.0 on Mohs scale; Color: Black to steel-grey; Luster: Submetallic, vitreous to brilliant; Crystal Structure: Amorphous (non-crystalline); Specific Gravity: 1.3-1.8; Fracture: Conchoidal (shell-like curves).
- Hardness
- 2
- Color
- Black to steel-grey
- Luster
- Submetallic, vitreous to brilliant
Identified More metamorphic →
Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness: 2.5-3.0 on Mohs scale; Color: Black to steel-grey; Luster: Submetallic, vitreous to brilliant; Crystal Structure: Amorphous (non-crystalline); Specific Gravity: 1.3-1.8; Fracture: Conchoidal (shell-like curves).
Formation & geological history
Formed through the regional metamorphism of bituminous coal. It involves high heat and pressure over millions of years, typically in folded mountain belts. Primarily dating from the Carboniferous Period (approx. 300 million years ago).
Uses & applications
Primarily used for heating residential and commercial buildings as it burns cleanly with little smoke. Also used in water filtration, as a reduction agent in metallurgy, and occasionally in jewelry (jet) or carving.
Geological facts
Anthracite contains the highest percentage of fixed carbon (86% to 98%) and the lowest amount of volatile matter of all coal types. It is often referred to as 'hard coal' and accounts for only about 1% of global coal reserves.
Field identification & locations
Identify in the field by its high luster, clean feel (does not soil fingers like softer coal), and conchoidal fracture. Common locations include the Appalachian Mountains in Pennsylvania, USA, parts of Wales, and China. Collectors look for high-gloss specimens with sharp edges.
More like this
