Definition
Shale is a fine-grained sedimentary rock which is formed by the compaction of silt and clay-size mineral particles
Arkose is a sedimentary rock, specifically a type of sandstone containing at least 25% feldspar
History
Origin
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France
Discoverer
Johann Gottlob Lehmann
Alexandre Brongniart
Etymology
From German Schalstein laminated limestone, and Schalgebirge layer of stone in stratified rock. From Old English scealu in its base sense of- thing that divides or separate,
From Auvergne region of France used by a French geologist Alexandre Brongniart in 1826 who applied this term to some feldspathic sandstones
Class
Sedimentary Rocks
Sedimentary Rocks
Sub-Class
Durable Rock, Medium Hardness Rock
Durable Rock, Hard Rock
Family
Group
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Other Categories
Fine Grained Rock, Opaque Rock
Coarse Grained Rock, Opaque Rock