Assertion: feather | /r/MadeOf | pigment
Facets:
Source sentences:
text: Darker feathers contain a pigment known as melanin.
text: The color of feathers can be provided in two ways: (1) the feathers can contain pigments, of which there are three types, melanins, carotenoids and porphyrins; and (2) the structure of the feather can provide either iridescent or noniridescent color.