Definition
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Etymology
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Limestone is a sedimentary rock composed mostly of calcite and aragonite, which are different crystal forms of calcium carbonate
From lime and stone in late 14th Century
Durable Rock, Medium Hardness Rock
Fine 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