Definition
Limestone is a sedimentary rock composed mostly of calcite and aragonite, which are different crystal forms of calcium carbonate
Chalk is a soft, white, powdery limestone consisting mainly of fossil shells of foraminifers
History
Origin
New Zealand
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Discoverer
Belsazar Hacquet
Unknown
Etymology
From lime and stone in late 14th Century
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, Medium Hardness Rock
Durable Rock, Soft Rock
Family
Group
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Other Categories
Fine Grained Rock, Opaque Rock
Fine Grained Rock, Opaque Rock