3 Minerals – An Introduction to Geology
Orthoclase feldspar (KAlSi 3 O 8), also called potassium feldspar or Kspar, is made of silica, aluminum, and potassium. Quartz and orthoclase feldspar are felsic minerals. Felsic is the compositional term applied to continental igneous minerals and rocks that contain an abundance of orthoclase feldspar.