Definition
Trachyte is a grey fine-grained volcanic rock which mainly consists of alkali feldspar
Mudstone is a fine-grained, dark gray sedimentary rock, which is formed from silt and clay and is similar to shale but has less laminations
History
Origin
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Discoverer
Alexandre Brongniart and René Just Haüy
William Smith
Etymology
From Greek trakhus rough’ or trakhutēs roughness
From the English mud and stone, from low German mudde and stainaz
Class
Igneous Rocks
Sedimentary Rocks
Sub-Class
Durable Rock, Medium Hardness Rock
Durable Rock, Soft Rock
Family
Group
Volcanic
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Other Categories
Fine Grained Rock, Opaque Rock
Fine Grained Rock, Opaque Rock