The V-Ray Rock Texture generates a procedural rock pattern using two colors or texture maps.  

||mat Network|| > V-Ray > Texture: Procedural > V-Ray Rock

The TexRock node provides inputs for controlling various texture properties. They correspond to parameters in the section below.

Color 1 – Controls the first of the two colors used by the V-ray Rock procedural.

Color 2 – Controls the second of the two colors used by the V-ray Rock procedural.

Mix Ratio – Controls the mix between Color 1 and Color 2. For more details, please see the Mix Ratio example below.

Grain Size – Controls the size of the fine grain features. For more details, please see the Grain Size example below.

Diffusion – Lower values make the resulting texture sharper, while higher values blur the texture details more. For more details, please see the Diffusion example below.

Wrap – Enables wrapping for the texture.

Default Color – Specifies the color when there are no valid UVW coordinates.

Mult – Specifies a strength multiplier for the texture color.

Offset – Color corrects the texture by adding the the RGB color values specified here to the RGB color values in the texture.

Invert – When enabled, inverts the resulting texture color.

Source – Specifies where the alpha channel is drawn from.

Alpha – Alpha channel is drawn from the texture.
Color – Alpha is generated from pixel intensity.
Opaque – Alpha channel is fully opaque.

Use – Differentiate between textures exported from different applications. You can choose between Color Intensity (3ds Max) and Color Luminance (Maya).

Mult – Specifies a multiplier for the texture alpha.

Offset – Specifies an additional offset for the texture alpha.

Invert – When enabled and Invert from Color Tweaks is also enabled, the resulting texture alpha is inverted as well.

Placement Type – Specifies the way the valid portion of the texture is applied.

Full – Uses the full valid portion of the texture.
Crop – Allows the user to specify a section of the texture using the parameters below. 
Place – Allows the user to specify a section of the texture and how to place it using the parameters below.

U – Specifies the U coordinate of the valid texture sector.

V – Spcifies the V coordinate of the valid texture sector.

W – Specifies the width of the valid texture sector.

H – Specifies the height of the valid texture sector.

Jitter – Controls the amount of random placement variation.

Tile U – Enables horizontal tiling.

Tile V – Enables vertical tiling.

Enabled – Enables noise for the texture.

Amount – Specifies the amount of noise to add to the texture.

Levels – Specifies the amount of noise iterations.

Size – Controls the scale of the noise.

Animated – Enables the noise to be animated.

Phase – Controls the noise phase.

Example: Mix Ratio