Assertion: obsidian's color | /r/CreatedBy | manganese
Facets:
value: in the mineralogical literature
type: LOCATION
value: by a large number of authors
type: OTHER
value: for over 100 years
type: TEMPORAL
Source sentences:
text: In the mineralogical literature, the pink color of rose quartz has been attributed to titanium, manganese, and iron by a large number of authors for over 100 years.