Assertion: obsidian | /r/HasProperty | natural glass
Facets:
Source sentences:
text: Obsidian is a natural glass formed by the meeting of lava from an erupting volcano with cold air or water, imbuing obsidian with all four elements: earth, fire, water, and air.
text: When lava ejects from a volcano and forms obsidian, the cooling process is fast enough that the obsidian is considered a natural forming glass.
text: Obsidian is a natural glass which is formed through volcanic activity by the cooling of molten lava.
text: Obsidian is a natural glass, often formed in volcanoes.
text: Obsidian is natural glass that was originally molten magma associated with a volcano .
text: Obsidian is natural glass that was originally molten magma associated with a volcano .
text: Obsidian is natural glass that was originally molten magma associated with a volcano.