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Is obsidian a rock?

In: Geology [Edit categories]

Answer:

Obsidian is an igneous glass not a rock, that forms when lava cools so rapidly that atoms are unable to arrange themselves into a crystalline structure. The result is a volcanic glass with a smooth uniform texture that breaks with a conchoidal fracture.

As rocks are by definition made from minerals which in turn have to be crystalline, obsidian by definition can not be a rock.

First answer by ID2858091780. Last edit by SBDW1. Contributor trust: 228 [recommend contributor ]. Question popularity: 1 [recommend question].

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Relevant answers:

What is an obsidian rocks?
An obsidian rock is an extrusive igneous rock that forms when a volcano erupts and has no time to crystallize, so it has a glassy texture. Obsidian rocks are generally black in color.
How are obsidian rocks different from igneous rock?
Obsidian is a form of an igneous rock that forms when molten rock material cools so rapidly that atoms are unable to arrange themselves into a crystalline structure.
What is the rock cycle of obsidian rocks?
Obsidian goes through the rock cycle by being exposed to sediment for too long
Why is obsidian considered a granitic rock?
Obsidian, even though it is a volcanic glass and an extrusive igneous rock, shares the same chemistry as intrusive granite; in other words they are both felsic igneous rocks.
Is obsidian a metamorphic rock?
No. Obsidian is an extrusive igneous glass.