Gerolsteiner Mineral Water is rich in minerals, but these minerals are dissolved and with the aid of carbonic acid, they are held in suspension in the water. Physical and chemical changes, for example, temperature, pressure or levels of carbonation can cause minerals to fall out that is, microscopic mineral elements can come together and become visible. Hence the light residue you can sometimes see on your glass after enjoying Gerolsteiner. The amount of solid but dissolved minerals in Gerolsteiner mineral water amounts to 800 (Naturell) to 2,500 mg/l (Sparkling). Several factors can prompt precipitation.