Feldspar is a very common igneous rock – more than half of the Earth‘s crust is made of feldspar. When molecules of aluminum, silica and oxygen get together with potassium, they combine to make the rock feldspar.
Feldspar often combines with another rock called quartz to make a much harder igneous rock called granite. Or, if feldspar gets in contact with another rock called pyroxene, those two rocks combine to make basalt.
When feldspar is in contact with wind or water, the wind and water gradually grind the feldspar down into tiny grains that become one kind of clay called kaolin. Kaolin is the extremely fine, white clay that Chinese porcelain is made of.