Feldspar is a type of rock that contains our primary fluxing material, the alkali metals (R2O).

The feldspars we use contain Sodium (Na2O), Potassium (K2O) and Lithium (Li2O) which bring down the melting temperature of our materials.

The generic formula for a feldspar is R2O-Al2O3-6SiO2This means that for every fluxing molecule, we have one Alumina molecule and 6 Silica molecules. Silica is everywhere.

Feldspars are commonly referred to by their various brand names.

Custer and G200 are brands of Potassium feldspar and the generic formula is K2O-Al2O3-6SiO2

Minspar and Kona F-4 are brands of Sodium feldspar and the generic formula is Na2O-Al2O3-6SiO2

Nepheline Syenite is a brand of feldspathoid.  It is similar to a feldspar but it has a slightly different formula.  The generic formula for Nepheline Syenite is 3Na2O-K2O-4Al2O3-9SiO2

Spodumene  and Petalite are feldspathoids and sources of Lithium.  The generic formula for Spodumene is Li2OAl2O3‑4SiO2. The generic formula for Petalite is Li2OAl2O3‑8SiO2

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