'Blueberries' Inside 'Popcorn'

Figure 1	Figure 2

This view from the microscopic imager on NASA's Mars Exploration Rover Opportunity shows a type of light-colored, rough-textured spherules scientists are calling "popcorn" in contrast to the darker, smoother spherules called "blueberries." It is the lower-left frame of a four frame mosaic (see PIA06778) taken on sol 199 (Aug. 15, 2004). The red arrows in figure 1 indicate blueberries partially covered with popcorn material. The yellow arrows in figure 2 point to something even more puzzling. These darker toned, irregularly shaped objects might be blueberry fragments emerging from the popcorn material as the pebble weathers away. It is still not clear whether all of the popcorn spherules contain blueberry material.