1 Definition
1.1 Definition
Coal is a combustible black or brownish-black sedimentary rock usually occurring in rock strata in layers called coal beds
Ignimbrite is a volcanic rock consisting mainly of pumice fragments, formed by the consolidation of material deposited by pyroclastic flows
1.2 History
1.2.1 Origin
1.2.2 Discoverer
John Peter Salley
Patrick Marshall
1.3 Etymology
From the Old English term col, which has meant mineral of fossilized carbon since the 13th century
From Latin ignis fire + imber, imbr- shower of rain, storm cloud + -ite
1.4 Class
Sedimentary Rocks
Igneous Rocks
1.4.1 Sub-Class
Durable Rock, Soft Rock
Durable Rock, Medium Hardness Rock
1.5 Family
1.5.1 Group
1.6 Other Categories
Coarse Grained Rock, Fine Grained Rock, Medium Grained Rock, Opaque Rock
Fine Grained Rock, Opaque Rock