Laguna Custer Feldspar

Custer Feldspar, so names because it is a type of mineral mined in Custer, SD, is made up of silica and alumina combined with sodium and potassium oxides,

It is used in both clay and glaze formulas. In glazing, Custer felsdpar is popular for achieving matte glaze effects.

It has a melting point of 12000 C.