On sol 167, Spirit looked at a bit of soil called "Jaws" with the alpha particle X-ray spectrometer and microscopic imager. Then the rover completed a drive intended to put it into position to analyze "Pot-of-Gold" with the instruments on its robotic arm. The drive moved Spirit farther than expected though, and the rover ended up directly over the rock. That position prevented any observations with the instrument deployment device.
On sol 168, rover planners commanded Spirit to "bump" backward, into a position where the rock abrasion tool could make contact with Pot-of-Gold. This was successful, and Spirit spent the rest of the time taking images of the surrounding area with its panoramic and navigation cameras.
On sol 169, Spirit successfully operated its rock abrasion tool on Pot-of-Gold, grinding away the top .2 millimeters (.008 inches) of rock from the high points. The procedure took 1 hour and 45 minutes. Pot-of-Gold posed a special challenge to the rover team because it is quite small -- only slightly larger than the rock abrasion tool instrument itself. The rock abrasion tool inflicts about 6.8 kilograms (15 pounds) of pressure on its rock targets, and smaller rocks aren't necessarily stable enough to resist this.
Before and after pictures of Pot-of-Gold showed that the rock was moved by the rock abrasion tool procedure. That movement, plus possible slippage where the tool contacts the rock, resulted in only intermittent contact during the grinding operation. After the grind was complete, Spirit placed the alpha particle X-ray spectrometer on the freshly exposed area in preparation for an operation later that night.
On Sol 170, Spirit awoke to stop the alpha particle X-ray integration, took miniature thermal emission spectrometer and panoramic camera images of some local track marks, took more microscopic images of the newly exposed Pot-of-Gold, then placed the Mo"ssbauer instrument on the site for a 21-hour overnight observation.