sedimentary
Likely anthracite coal
Anthracite, a high-rank coal composed chiefly of carbon
AI-generated identification · may be incorrectDark gray to black, compact, and shiny in patches with irregular fracture; hardness about 2–3 Mohs. The photograph does not show enough detail to confirm its identity or determine crystal structure and specific gravity.
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Physical properties
Dark gray to black, compact, and shiny in patches with irregular fracture; hardness about 2–3 Mohs. The photograph does not show enough detail to confirm its identity or determine crystal structure and specific gravity.
Formation & geological history
Forms when buried coal deposits are subjected to strong heat and pressure, typically during regional metamorphism; its age depends on the original plant-rich deposit.
Uses & applications
Burned as a high-carbon fuel and collected as a geological specimen; anthracite is also used in some filtration applications.
Geological facts
Anthracite is the highest-rank coal and generally burns hotter and with less smoke than lower-rank coal.
Field identification & locations
Look for a hard, compact black material with a bright, sometimes metallic-looking sheen and no visible wood structure; common in coalfields such as Pennsylvania’s Appalachian region. The image alone cannot distinguish it reliably from other dark rocks or minerals.
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