Sols 4088-89, 4091, July 25, 26, 28, 2015. The Microscopic Imager has been studying a target named Pvt. Reubin Field, commemorating another of the Lewis & Clark Corps of Discovery. (His name is variously spelled as Reuben and as Fields.)
The rock is part of the wind-swept “pavement” at the head of Marathon Valley. Click the image to enlarge.
Below: the Hazcam’s view of the site on Sol 4091 (contrast adjusted).
Opportunity raw images, its latest mission status, a location map. and atmospheric opacity, known as tau.