mottle -- (an irregular arrangement of patches of color; "it was not dull grey as distance had suggested, but a mottle of khaki and black and olive-green")
Overview of verb mottle
The verb mottle has 2 senses
mottle, streak, blotch -- (mark with spots or blotches of different color or shades of color as if stained)
mottle, dapple, cloud -- (colour with streaks or blotches of different shades)