Definition
Rhyolite is a fine-grained igneous rock which is rich in silica
Trachyte is a grey fine-grained volcanic rock which mainly consists of alkali feldspar
History
Origin
North America
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Discoverer
Ferdinand von Richthofen
Alexandre Brongniart and René Just Haüy
Etymology
From German Rhyolit, from Greek rhuax lava stream + lithos stone
From Greek trakhus rough’ or trakhutēs roughness
Class
Igneous Rocks
Igneous Rocks
Sub-Class
Durable Rock, Hard Rock
Durable Rock, Medium Hardness Rock
Family
Group
Volcanic
Volcanic
Other Categories
Coarse Grained Rock, Opaque Rock
Fine Grained Rock, Opaque Rock