Sand is a heterogeneous mixture because it is a granular substance composed of small particles of rocks or minerals. A heterogeneous mixture contains components that are not uniform throughout the mixture.
For example, sand can contain different grain sizes and small colored particles. Some other examples of heterogeneous mixtures are blood, gravel and the combination of oil and vinegar.
Sand cannot be an element because an element consists of only one type of atom, such as the element potassium. Similarly, sand is not a compound. Compounds are substances composed of two or more elements that are held together by a bond. The components of a compound are also in a definite ratio. Some examples of compounds are sodium chloride and water.