Pebble sections

I've missed most of the recent MER press conferences, and the web site seems
to be way behind the incoming raw pictures. What is the speculation about
the appearance of the spherical pebbles/inclusions that Opportunity's RAT
sectioned in the outcrop? They look like solid, mostly featureless (except
for the marks left by the grinding pad), spherical pieces of rock.

Also, where are the best online geological dictionaries?

JJ Robinson II
Houston, TX
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