North American G-200 (when last supplied, a 70:30 blend of G-200 HP and Minspar 200) is unavailable. The recommended recipe substitute now is G-200 EU (from Europe) or Mahavir (from India). Both feldspars have similar chemistry and melting behaviour to the original G-200.
For more information on G-200 EU feldspar, see the Digitalfire.com Reference Library of ceramic materials.