The "granules" of King George Island

Caption NASA originale:"This mosaic was made from frames acquired by the MI - Microscopic Imager on NASA's MER Spirit during Spirit's 1031st Martian Day, or Sol, on the Red Planet (such as Nov. 27, 2006). It shows a rock target called "King George Island" after the target was brushed by the Rover's RAT - Rock Abrasion Tool.
The mosaic covers approx. 6 cm (2,4") across and shows the granular nature of the rock exposure. The grains are typically about 1 mm (0,04") wide.
Data from the Rover's Mössbauer Spectrometer provides evidence that they have an enhanced amount of the mineral Hematite relative to surrounding soils".