feldspar

/ˈfɛldˌspɑr/
noun
  1. A common type of mineral found in rocks, often white, pink, or gray, used in making ceramics and glass.
    • The pottery studio uses ground feldspar to create a smooth glaze on their cups.
    • The granite countertop sparkled because it contained a lot of feldspar.
    • Geologists identified the rock sample as rich in feldspar and quartz.