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 water-soluble mineral sediment resulting from concentration and crystallization by evaporation from an aqueous solution
History
Origin
Ethiopia
USA
Discoverer
Obsius
Usiglio
Etymology
From Latin obsidianus, misprint of Obsianus (lapis) (stone) of Obsius
From a sediment left after the evaporation
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, Medium Grained Rock, Opaque Rock