Definition
Gritstone or grit is a hard, coarse-grained, siliceous sandstone
Trachyte is a grey fine-grained volcanic rock which mainly consists of alkali feldspar
History
Origin
Pennines, England
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Discoverer
J.J. Ferber
Alexandre Brongniart and René Just Haüy
Etymology
From Grit + Stone
From Greek trakhus rough’ or trakhutēs roughness
Class
Sedimentary Rocks
Igneous Rocks
Sub-Class
Durable Rock, Hard Rock
Durable Rock, Medium Hardness Rock
Family
Group
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Volcanic
Other Categories
Coarse Grained Rock, Opaque Rock
Fine Grained Rock, Opaque Rock