Grains of sand are really very tiny particles of rock. It takes time and a special kind of weather to turn rock into sand. Rain, frost, and wind can do the job. On beaches, the tide hitting against the rocks forms sand. Salt water, too, forms sand by dissolving minerals in the rocks. Since rocks are made up of minearals and since sand comes from rocks, you would expert to find lots of minerals in sand. There are, in fact, large quantities of quartz and also some lime gypsum, feldspar, and even iron ore in sand.