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