Assertion: tourmaline's color | /r/HasProperty | black
Facets:
Source sentences:
text: The commonest color is a deep red, also, brown, yellow, apple-green, black; powder, white; luster, glassy or resinous ; H = 6.5 to 7.5; G = 3.15 to 4.3; crystals, in cubic system; has no true cleavage, but sometimes has a regular break, called parting.