hornstone
/ˈhɔːrnˌstoʊn/
noun
- A hard, dark-colored rock that looks like horn, often used in making tools or arrowheads.
- Archaeologists found arrowheads made of hornstone at the ancient campsite.
- The cliff was made of a shiny black hornstone that broke into sharp pieces.
- He collected a piece of hornstone to practice flint knapping.