Definition of a rock and the difference between a rock and a mineral ?

A rock is a mixture of one or more minerals. There are many kinds of rocks, and we will learn about them in following lessons. At this point, it is sufficient to know that a rock is a very general term that applies to most any hard, naturally occurring mineral deposit found at the surface of our planet. Rocks are usually a mixture of minerals, either melted or compressed together by forces within the Earth.

A common and excellent example of a typical rock is granite. Granite is a mixture of silica and feldspar minerals. You can easily see, with the naked eye, the different mineral deposits that make up this rock. A picture of granite is available in the multimedia enhancement of this lesson.