Sand is a mixture, not a compound. Sand is classified as a heterogeneous mixture because it does not have the same properties, composition and appearance throughout the mixture. A homogeneous mixture has a uniform mix throughout.
Sand is found over much of Earth's surface, blanketing beaches, riverbeds and deserts. It is made up of small particles of rock, minerals and other materials. The composition of sand varies depending on its location. Silicon dioxide in the form of quartz is the most common component of sand. It is found in an array of colors, including pink, green, black, tan and white.