metamorphic
Anthracite Coal
Anthracite
Hardness: 2.5-3.0 on Mohs scale; Color: Jet black to silver-grey; Luster: Submetallic, vitreous (glassy); Crystal structure: Amorphous; Cleavage: None (conchoidal fracture); Specific gravity: 1.3-1.8
- Hardness
- 2
- Color
- Jet black to silver-grey
- Luster
- Submetallic, vitreous (glassy)
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Physical properties
Hardness: 2.5-3.0 on Mohs scale; Color: Jet black to silver-grey; Luster: Submetallic, vitreous (glassy); Crystal structure: Amorphous; Cleavage: None (conchoidal fracture); Specific gravity: 1.3-1.8
Formation & geological history
Formed through the regional metamorphism of bituminous coal in sedimentary basins. It occurs when organic matter is subjected to intense heat and pressure over millions of years, typically during mountain-building events (orogenies). Most was formed during the Carboniferous period.
Uses & applications
Historically used as a high-grade fuel for domestic heating and industrial steam production due to low sulfur and high carbon content. Today, it is used in steel making, water filtration, and as a material for carvings and jewelry.
Geological facts
Anthracite is the highest rank of coal, containing 86% to 98% carbon. Unlike other coals, it burns with a short blue flame and produces very little smoke. It is often referred to as 'hard coal.'
Field identification & locations
Identify in the field by its high luster (very shiny), black streak, and light weight relative to its size. It does not soil fingers like softer bituminous coal. It is commonly found in the Appalachian mountains of Pennsylvania, USA, and parts of South Wales and China.
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