Definition
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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
Tonalite is a coarse-grained plutonic rock consisting mainly of sodic plagioclase, quartz, and hornblende or other mafic minerals with phaneritic texture
From Tonale Pass, northern Italy, + -ite1
Coarse Grained Rock, Fine Grained Rock, Medium Grained Rock, Opaque Rock