type of mineral common in crystalline rocks, 1785, earlier feldspath (1757), from older German Feldspath (Modern German Feldspat), from Feld "field" (see field (n.)) + spath "spar, non-metallic mineral, gypsum" (see spar (n.2)); spelling influenced by English spar "mineral." Related: Feldspathic.[feldspar etymology, feldspar origin, 英语词源]