Definition
Chalk is a soft, white, powdery limestone consisting mainly of fossil shells of foraminifers
Phonolite is an uncommon extrusive igneous rock volcanic rock of intermediate chemical composition between felsic and mafic
History
Origin
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Discoverer
Unknown
Unknown
Etymology
From old English cealc chalk, lime, plaster; pebble, from Greek khalix small pebble, in English transferred to the opaque, white, soft limestone
From the Greek meaning sounding stone because of the metallic sound it produces if an unfractured plate is hit
Class
Sedimentary Rocks
Igneous Rocks
Sub-Class
Durable Rock, Soft Rock
Durable Rock, Medium Hardness Rock
Family
Group
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Other Categories
Fine Grained Rock, Opaque Rock
Fine Grained Rock, Opaque Rock