The name feldspar is given to a group of minerals that contain alumina and silica in their chemistry (including aluminium silicates of soda, potassium or lime). About 60% of the earth’s crust is made from feldspar making it the most abundant group of minerals.
More than 70% of the feldspars produced in the EU are used in the ceramic industry and most of the rest is in glass production. In ceramics, manufacturing feldspar is the second most important ingredient after clay. Feldspar does not have a strict melting point since it melts gradually over a range of temperatures which greatly facilitates the melting of quartz and clays. Feldspar improves the strength, toughness and durability of the ceramic body and cements the crystalline phase of other ingredients, softening, melting and wetting other batch constituents.
In the manufacture of glass, the alkali content in feldspar acts as flux, lowering the glass batch melting temperature and thus reducing production costs.