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
Whiteschist is an uncommon rock type belonging to a class of metamorphic rock, this is formed at high-ultra-high pressures
History
Origin
Ethiopia
Tasmania
Discoverer
Obsius
Unknown
Etymology
From Latin obsidianus, misprint of Obsianus (lapis) (stone) of Obsius
From French schiste, Greek skhistos i.e. split
Class
Igneous Rocks
Metamorphic Rocks
Sub-Class
Durable Rock, Medium Hardness Rock
Durable Rock, Soft Rock
Family
Group
Volcanic
-
Other Categories
Opaque Rock
Fine Grained Rock, Medium Grained Rock, Opaque Rock