Definition
Origin
Discoverer
Etymology
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Other Categories
Arkose is a sedimentary rock, specifically a type of sandstone containing at least 25% feldspar
From Auvergne region of France used by a French geologist Alexandre Brongniart in 1826 who applied this term to some feldspathic sandstones
Coarse Grained Rock, Opaque Rock
Chalk is a soft, white, powdery limestone consisting mainly of fossil shells of foraminifers
From old English cealc chalk, lime, plaster; pebble, from Greek khalix small pebble, in English transferred to the opaque, white, soft limestone
Fine Grained Rock, Opaque Rock