Custer Feldspar | repurposedMATERIALS
Custer feldspar is a widelyused potash, or potassiumbearing, feldspar. This means that the feldspar contains more potassium than sodium (as indicated by the socalled ''soda spars''). This inclusion of potassium means that Custer (along with other potash spars) melts at about 1200C, which is a bit higher than the melting temperature of soda spars.