Feldspar - digitalfire.com
commonly used forms (as often labeled commercially) — albite "sodium feldspar" Na 2 O, Al 2 O 3, 6SiO 2 — sanidine "potassium feldspar" K 2 O, ... helped when and if needed by non-alkali fluxes and/or other alkalis not present in the particular feldspar(s) being used. Fusion temperatures for the great variety of feldspars are, all ...