Definition
Origin
Discoverer
Etymology
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Other Categories
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
Lamprophyre is uncommon igneous rocks primarily occurring as dikes, lopoliths, laccoliths, stocks and small intrusions
From Greek lampros bright and shining + porphureos purple
Durable Rock, Medium Hardness Rock
Coarse Grained Rock, Fine Grained Rock, Opaque Rock