Assertion: obsidian | /r/MadeOf | the meeting of lava
Facets:
value: with water
type: OTHER
value: from an erupting volcano
type: OTHER
value: with cold air
type: OTHER
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.