Silicon dioxide is the chemical name of sand.
There is no chemical formula for the sand. By default sand formula treated as sio2. Sand is a mixture of multiple different minerals . sand has a variety of color depending on the location. sand is a mixture of Silica (SiO2), Calcium Silicate (CaSiO4), Calcium Nitride (Ca3N2), Silicon Nitride (Si3N4), Aluminium Nitride (AlN3), Alumina (Al2O3), Borazone "Boron Nitride" (BN), Magnesium Oxide (MgO), Silicon Oxysulfide (SiOS), Lithium Silicate (Li2SiO4) and other oxides/nitrides of a multitude of metals.