How would something like concrete be classified? I'm not sure of all of the things that go into the mixture, but I know gravel, sand, and water are big components. What I don't know is what substance holds everything together.
Is it possible to have something that is both part heterogeneous and part homogeneous? For example, you could theoretically use a microscope and separate every single rock and sand particle from a block of concrete, but wouldn't the water have chemically bonded with something else to the point where it couldn't be separated again?