Question

$what \: is \: obsidian?$
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Answer 1

Answer:

Obsidian is a naturally occurring volcanic glass formed as an extrusive igneous rock. Obsidian is produced when felsic lava extruded from a volcano cools rapidly with minimal crystal growth. It is commonly found within the margins of rhyolitic lava flows known as obsidian flows. 

Answer 2

Answer:

Obsidian. Rondi: Everyone, meet Obsidian , an igneous rock that from melted rock, or magma. Obsidian is an "extrusive” rock, which means it is made from magma that erupted out of a volcano. If it was an igneous rock that formed from magma underground and did not erupt, it would have been called an "intrusive" rock.

» Optical properties: Translucent

» Color: Deep black or blackish green

» Other characteristics: Texture: Smooth; glassy

» Specific gravity: c. 2.4

» Luster: Vitreous

» Fracture: Conchoidal