Definition
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Etymology
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Other Categories
Coal is a combustible black or brownish-black sedimentary rock usually occurring in rock strata in layers called coal beds
From the Old English term col, which has meant mineral of fossilized carbon since the 13th century
Coarse Grained Rock, Fine Grained Rock, Medium Grained Rock, Opaque Rock
Taconite is a low-grade iron ore which belongs to sedimentary rock and containing about 27% iron and 51% silica
Western Australia, Minnesota
From the name of Taconic Mountains in New England
Durable Rock, Medium Hardness Rock
Coarse Grained Rock, Opaque Rock