Definition
It is a metamorphic magnesium rich rock because it is composed of the mineral talc
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
History
Origin
USA
Ethiopia
Discoverer
Unknown
Obsius
Etymology
From 17th century, because of its greasy feel and use like a soap
From Latin obsidianus, misprint of Obsianus (lapis) (stone) of Obsius
Class
Metamorphic Rocks
Igneous Rocks
Sub-Class
Durable Rock, Soft Rock
Durable Rock, Medium Hardness Rock
Family
Group
-
Volcanic
Other Categories
Fine Grained Rock, Opaque Rock
Opaque Rock