Easy Textures - Sand Stone

Start with a new image, Size 400x400, Background Color: White, 16 Million Colors.

Step 1:
Image - Special Filters - Add Noise.
Select Uniform and 10% Noise.

Step 2:
Colors - Grey Scale.
Colors - Increase Color Depth - 16 Million Colors.

Step 3:
Image - Normal Filters - Sharpen.
(At this stage the image looks almost totally white).
Set Foreground Color to White.
Image - Special Effects - Hot Wax Coating.

Step 4:
Image - Normal Filters - Sharpen More.
Do this procedure two times.

Step 5:
Image - Resample - Custom size = 200x200.
Then Image - Normal Filters - Sharpen.