Definition
Slate is a fine-grained, foliated, homogeneous metamorphic rock derived from an original shale-type sedimentary rock composed of clay or volcanic ash through low-grade regional metamorphism
Trachyte is a grey fine-grained volcanic rock which mainly consists of alkali feldspar
History
Origin
England
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Discoverer
Abraham Gottlob Werner
Alexandre Brongniart and René Just Haüy
Etymology
From Old French esclate, from esclat (French éclat)
From Greek trakhus rough’ or trakhutēs roughness
Class
Metamorphic Rocks
Igneous Rocks
Sub-Class
Durable Rock, Medium Hardness Rock
Durable Rock, Medium Hardness Rock
Family
Group
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Volcanic
Other Categories
Fine Grained Rock, Opaque Rock
Fine Grained Rock, Opaque Rock