This is a collection of rock materials for the Cycles engine in Blender. I have tried to reproduce the look of a variety of real rock types. They are quite detailed and are best used at close-up range.
Since one type of geologic rock can look quite differently depending on its detailed composition, and its impurities, I have included multiple variations for many rock types. The materials are free to use and modify, and you can see how they are done in the node editor.