ˈfelzˌpär, -l(d)ˌsp-, -pȧ(r noun
also feld·spath -path
( -s )
Etymology: feldspar part translation of obsolete German feldspath (now feldspat ); feldspath from obsolete German feldspath (now feldspat ), from German feld field (from Old High German) + obsolete German spath spar (now spat ), from Middle High German spat, spāt; akin to Old High German spān chip of wood — more at spoon
: any of a group of usually white or nearly white, flesh-red, bluish, or greenish minerals that are closely related in crystalline form, that are all aluminum silicates with potassium, sodium, calcium, or barium, that occur in crystals and crystalline masses which are vitreous in luster and break rather easily in two directions at approximately right angles to each other, that are essential constituents of nearly all crystalline rocks (as granite, gneiss, most kinds of basalt, and trachyte), that on decomposition yield a large part of the clay of the soil and also the mineral kaolinite, and that include the monoclinic species orthoclase and celsian and the triclinic species microcline, anorthoclase, anorthite, albite, and other plagioclases (hardness 6-6.5, specific gravity 2.5-2.9)