Assertion: ivory | /r/MadeOf | two materials
Facets:
value: unlike rhino horn
type: OTHER
Source sentences:
text: Unlike rhino horn, which is made almost solely of keratin, ivory consists of two materials: a highly ordered scaffolding made of collagen—the protein that gives structure to skin, tendons, and other tissues—embedded with hydroxyapatite, a hard, calcium-based mineral also found in bone.