Sol 4016, May 12, 2015. The rock named Harry H. Knight (for a St. Louis businessman who funded a large part of Lindbergh’s trans-Atlantic flight in 1927) has a distinctive bluish color in this false-color image. Holger Isenberg created the image using filtered Pancam images. (Click the image to load a larger version in a new browser tab.)
Other rocks in the immediate area show the same color, suggesting they have a similar mineralogy.
With regard to Opportunity itself, from the May 18 rover status bulletin: “On the morning of Sol 4017 (May 13, 2015), the rover experienced a vehicle reset during the high-gain antenna (HGA) pass. A bad address was reported with a range outside of any address space used by the rover’s avionics. The cause of the reset is not known at this time. The project is in the process of restoring the rover back to master sequence control.”
Opportunity raw images, its latest mission status, a location map. and atmospheric opacity, known as tau.