Assertion: obsidian's composition | /r/DefinedAs | containing mostly quartz
Facets:
Source sentences:
text: The mineralogical composition of rhyolite is defined as containing mostly quartz and feldspar with a total silica content of more than 68%.
text: The mineralogical composition of rhyolite is defined as containing mostly quartz and feldspar with a total silica content of more than 68%.