sedimentary
Coal (Anthracite)
Anthracite (Metamorphosed Coal)
Hardness: 2.5-3.0 Mohs; Color: Iron-black to grayish-black; Luster: Sub-metallic to vitreous; Crystal Structure: Amorphous (non-crystalline); Cleavage: Conchoidal fracture; Specific gravity: 1.3-1.4
- Hardness
- 2
- Color
- Iron-black to grayish-black
- Luster
- Sub-metallic to vitreous
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Physical properties
Hardness: 2.5-3.0 Mohs; Color: Iron-black to grayish-black; Luster: Sub-metallic to vitreous; Crystal Structure: Amorphous (non-crystalline); Cleavage: Conchoidal fracture; Specific gravity: 1.3-1.4
Formation & geological history
Formed through the accumulation of plant matter in swampy environments (peat), which then undergoes burial and high pressure/temperature over millions of years (carbonization). This specific high-rank carbon specimen indicates low-grade metamorphism of bituminous coal.
Uses & applications
Primarily used as a fuel source for residential and industrial heating. Known as 'smokeless fuel'. Some high-quality specimens are used in carvings or jewelry (jet).
Geological facts
Anthracite contains the highest percentage of fixed carbon (86%-98%) and the lowest amount of volatile matter among all types of coal. It burns with a short, blue, and smokeless flame.
Field identification & locations
Identify by its clean feel (doesn't leave much black residue on hands compared to soot), metallic luster, and relative lightness. Commonly found in folded mountain belts like the Appalachians (Pennsylvania) or South Wales.
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