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
Basaltic Trachyandesite is an extrusive igneous rock which is a type of Basalt rock and is formed by the rapid cooling of basaltic lava exposed at or very near the Earth's surface
History
Origin
Ethiopia
-
Discoverer
Obsius
Unknown
Etymology
From Latin obsidianus, misprint of Obsianus (lapis) (stone) of Obsius
From its mineral and compound content and its relation with Basalt and Andesite rock
Class
Igneous Rocks
Igneous Rocks
Sub-Class
Durable Rock, Medium Hardness Rock
Durable Rock, Medium Hardness Rock
Family
Group
Volcanic
Volcanic
Other Categories
Opaque Rock
Fine Grained Rock, Opaque Rock