Group of very common minerals which make up 40% of the continental crust (not to be confused with oceanic crust). They are part for about 60% of the all rocks that form the Earth’s crust. They can be involved in the mineralogic composition of almost all rocks. More generally, it is a group of rock-forming, aluminium tectosilicate minerals, also containing other cations such as sodium, calcium and potassium.

They are the largest group of minerals and, together with clays, they are one of the main inorganic raw materials involved in the production of ceramic tiles.

Their features change according to their chemical composition, the conditions under which they were formed, and the geological environment conditions.

Feldspar do not have a specific color (they are allochromatic) but they take on the color depending on the impurities that they may contain: red, green, yellow, black, grey.

Their hardness is lower than that of quartz: they are sixth in the Mohs hardness scale.