This composite image from the panoramic camera on NASA's Mars Exploration Rover Spirit gives an approximately true-color rendering of a daisy-like pattern of brushed circles that Spirit produced on a rock called "Route 66." Spirit used the rock abrasion tool to complete this 6-position "RAT daisy" on sol 99. It took this image on sol 100, April 14, 2004.
The purpose for these large brushings is to create a large enough patch of treated surface area for the miniature thermal emission spectrometer to analyze. Scientists had previously conducted a brushing like this one on the rock "Mazatzal." The brushed area of Route 66 looks very different from the brushed area of Mazatzal, leading scientists to think that the rocks although both light in tone actually have different coating types.