1 Definition
1.1 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
Gossan is intensely oxidized, weathered or decomposed rock, usually the upper and exposed part of an ore deposit or mineral vein.
1.2 History
1.2.1 Origin
1.2.2 Discoverer
1.3 Etymology
From Latin obsidianus, misprint of Obsianus (lapis) (stone) of Obsius
From Cornish gossen from gos, blood from Old Cornish guit
1.4 Class
Igneous Rocks
Metamorphic Rocks
1.4.1 Sub-Class
Durable Rock, Medium Hardness Rock
Durable Rock, Medium Hardness Rock
1.5 Family
1.5.1 Group
1.6 Other Categories
Opaque Rock
Fine Grained Rock, Medium Grained Rock, Opaque Rock