Assertion: feldspar mineral | /r/HasAspect | a vitreous
Facets:
value: to pearly luster on cleavage faces
type: LOCATION
Source sentences:
text: All feldspar minerals are usually translucent to transparent, display two directions of cleavage that intersect at approximately 90 degrees, have a vitreous to pearly luster on cleavage faces, and have a specific gravity between about 2.5 and 2.6.