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
Conglomerate is a sedimentary rock which forms from rounded gravel and boulder sized clasts which are cemented together in a matrix
History
Origin
Ethiopia
Italy
Discoverer
Obsius
Unknown
Etymology
From Latin obsidianus, misprint of Obsianus (lapis) (stone) of Obsius
From Latin conglomeratus, to roll together, i.e. from com together + glomerare to gather into a ball, from glomus (genitive glomeris) a ball
Class
Igneous Rocks
Sedimentary Rocks
Sub-Class
Durable Rock, Medium Hardness Rock
Durable Rock, Soft Rock
Family
Group
Volcanic
-
Other Categories
Opaque Rock
Coarse Grained Rock, Opaque Rock