FELSPAR (FELDSPAR) fĕl’ spar, the name of the most important group of rock-forming minerals. The feldspars are alumino-silicates of potassium, sodium, calcium or barium and are generally white, gray or pale shades of orangered. Green feldspar (Exod 28:17; 39:10; Ezek 28:13, NEB) is generally a variety of the potassium feldspar, microcline. This is referred to as amazonstone and is sometimes cut and polished as an ornamental stone. Amazonstone occurs in the Ilmen Mts. and at other points in the Urals, in Italy and in the gembearing pegmatites of Madagascar.