Can you state some facts about rocks?

Most rocks are a mixture of minerals. Metamorphic rocks, for example, are made when existing rocks are introduced to heat and pressure. Diamonds - made of carbon - are a good example. Marble is another example. Because of this process, metamorphic rocks often start as sedimentary or igneous rocks. Sedimentary rocks are created when the layers of sediment in a lake or the ocean are compressed.

The rock will have parts of each layer. Igneous rocks are formed when magma cools on the surface of the earth, and then chips off of the large layer of magma. These form most after a volcanic eruption. However, since most rocks we see today are either sedimentary or metamorphic, the only true statement is that most rocks are a mixture of minerals.