This is one of over 5156 textures generated by Filter Forge, a Photoshop plugin that allows you to create your own filters.
With Filter Forge, you can:
To open this filter, you must have Filter Forge 1.0 or higher installed on your computer. If you don't have it installed yet, click here to download Filter Forge
Blending two different sizes of rock noise together. Some results tend to create a repetitive texture when viewed from afar, however a few variations and alpha blending them together could work if it was to be used in a game level.