noun

• An abundant rock-forming mineral typically occurring as colorless or pale-colored crystals and consisting of aluminosilicates of potassium, sodium, and calcium.

  ‘Quartz is associated most commonly with aegirine and potassium feldspar as well as zircon.’

  More example sentences

  • ‘Larger crystals of feldspar and quartz dominate the host rock.’
  • ‘These granite dikes are composed almost totally of potassium feldspar and quartz.’
  • ‘Minerals such as feldspar, which are insoluble in water, will not give a positive test.’
  • ‘Its most abundant mineral is feldspar, which accounts for two-thirds of the Earth's crust.’