Definition
Gritstone or grit is a hard, coarse-grained, siliceous sandstone
Phonolite is an uncommon extrusive igneous rock volcanic rock of intermediate chemical composition between felsic and mafic
History
Origin
Pennines, England
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Discoverer
J.J. Ferber
Unknown
Etymology
From Grit + Stone
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, Hard Rock
Durable Rock, Medium Hardness Rock
Family
Group
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Other Categories
Coarse Grained Rock, Opaque Rock
Fine Grained Rock, Opaque Rock