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Obsidian and Anthracite Definition


Definition

Definition
Anthracite is a type of sedimentary rock which is hard and is variety of coal that has high luster   
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
Pennsylvania, U.S.   
Ethiopia   

Discoverer
Unknown   
Obsius   

Etymology
From Greek anthrakites, from anthrax, anthrak meaning coal   
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
Not Applicable   
Volcanic   

Other Categories
Coarse Grained Rock, Fine Grained Rock, Medium Grained Rock, Opaque Rock   
Opaque Rock   

Texture >>
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