Assertion: carbon black's carbon | /r/HasAspect | more than one refractive index
Facets:
value: by heating them
type: MANNER
Source sentences:
text: White carbon is a crystalline soft, transparent and birefringent (having more than one refractive index) allotrope of carbon made first in 1969 from graphite crystals by heating them to a high temperature (4130°F/2277°C) at low pressure.