Probably a heterogeneous mixture.
If two or more substances are combined together physically (as in no chemical reaction occurs), they form a mixture.
There are two classes of mixtures:
A homogeneous mixture is one in which the components are evenly dispersed throughout; it is also called a solution.
A heterogeneous mixture is one in which the components do NOT spread evenly throughout, and is often visibly so.
Since the composition is indefinite in a heterogeneous mixture, the answer to your question is a heterogeneous mixture.