Definition
Obsidian is a naturally occurring volcanic glass formed as an extrusive igneous rock. It is produced when felsic lava extruded from a volcano cools rapidly with minimum crystal growth
A sedimentary rock, deposit of a submarine turbidity currents and are composed of layered particles
History
Origin
Ethiopia
European Foreland Basins
Discoverer
Obsius
Arnold H. Bouma
Etymology
From Latin obsidianus, misprint of Obsianus (lapis) (stone) of Obsius
From Medieval Latin turbiditas, from Latin turbidus (turbid). Turbidity current is from 1939
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
Opaque Rock
Coarse Grained Rock, Fine Grained Rock, Opaque Rock