CUSTER SHORTAGE INFORMATION: https://shop.brackers.com/this-just-in/gerstley-custer-and-epk-issues/
Custer Feldspar is a potash feldspar.
Feldspar is a large group of minerals which have decomposed from granite and igneous rocks and are thus allied to clay. The main group consists of the alumino-silicates of potassium, sodium, calcium, and, more rarely, barium. The ideal formulas, never quite achieved in nature are:
Potash Feldspar, Orthoclase Microline, K2.Al2O3.6SiO2
Soda Feldspar, Albite, Na2O. Al2O3.6SiO2
Lime Feldspar, Anorthite, CaO.Al2O3.2SiO2
Feldspars are the most useful minerals in ceramics, apart from clays. Used as a primary flux above 1200°C (2192°F) and a secondary flux in earthenware. - p. 108, Illustrated Dictionary of Practical Pottery, 3rd Ed. by Robert Fournier
Feldspar is a large group of minerals which have decomposed from granite and igneous rocks and are thus allied to clay. The main group consists of the alumino-silicates of potassium, sodium, calcium, and, more rarely, barium. The ideal formulas, never quite achieved in nature are:
Potash Feldspar, Orthoclase Microline, K2.Al2O3.6SiO2
Soda Feldspar, Albite, Na2O. Al2O3.6SiO2
Lime Feldspar, Anorthite, CaO.Al2O3.2SiO2
Feldspars are the most useful minerals in ceramics, apart from clays. Used as a primary flux above 1200°C (2192°F) and a secondary flux in earthenware. - p. 108, Illustrated Dictionary of Practical Pottery, 3rd Ed. by Robert Fournier
50# bag; blue bag, black text Pacer Custer Feldspar
