Assertion: obsidian | /r/HasAspect | distinct color
Facets:
value: not only occasionally
type: TEMPORAL
value: like the greenish obsidian from pachuca
type: LOCATION
Source sentences:
text: Obsidian from a particular site not only occasionally has a distinct color, like the greenish obsidian from Pachuca, but an examination of the chemical trace elements in any given sample can nearly always identify the region or even the specific quarry from which it was mined.