A Rock Like None Before, Brushed
"Scientists viewed a rock like none seen before on Mars when NASA's Mars Exploration Rover Spirit brushed the surface and took magnified images of this rock dubbed "Wishstone." The circular area of interest, measuring approximately 5 centimeters (2 inches) in diameter, revealed darker pieces of material randomly distributed within a lighter-colored matrix. The rock has poorly sorted granular material, with grain sizes ranging from fine to coarse and some grains that are very angular in shape. Spirit used its microscopic imager on martian day, or sol, 333 (Dec. 9, 2004) to take the four individual frames that are combined into this mosaic view."
http://marsrovers.jpl.nasa.gov/gallery/press/spirit/20041230a.html


Curious are the dark, smooth inclusions apparent in the rock. These might be similar to the smooth, glassy inclusions seen by Spirit in Humphrey and Mazatzal rocks.
Alternatively, they could be examples of, apparent, sedimentary films seen at the Opportunity site:

From: rgregorycl...@yahoo.com (Robert Clark)
Newsgroups: sci.astro,alt.sci.planetary,sci.geo.geology,sci.ge o.mineralogy,sci.bio.misc
Subject: Sedimentary films at Opportunity site.
Date: 18 Mar 2004 16:26:04 -0800
http://groups-beta.google.com/group/sci.astro/msg/11a829ece45426b7


Clays perhaps?


Bob Clark

Here are some examples of the inclusions I mean. They appear throughout the RATTed area:

dark inclusions
http://sciforums.com/attachment.php?attachmentid=3654


Bob Clark

NASA said another rock in Gusev was high in phosphorus: Wishing Well rock.
Here is an MI of Wishing Well:

http://www.lipfordm.com/wtsi/p-2M158146955EFFA269P2959M2M1-90.jpg

The dark material around the right, inside rim of the RATTed area also appears to have the soft consistency as of clay.

Bob Clark

Here is a close-up of part of this dark, soft material in this rock:

dark, soft material
http://sciforums.com/attachment.php?attachmentid=3690


Bob Clark