Sand is composed of small rock and mineral particles.

Definition of Substance Types:

Element (A): A pure substance consisting of only one type of atom.

Compound (B): A substance formed when two or more elements are chemically bonded.

Isotope (C): Atoms of the same element with different numbers of neutrons.

Mixture (D): A combination of two or more substances that are not chemically bonded.

Composition of Sand: Sand is composed of various small rock and mineral particles, which are physically combined but not chemically bonded.

Conclusion: Sand is a mixture.

References:

Properties of Mixtures: Characteristics and examples of mixtures in physical science.