"Paul Henney" wrote:

Ian,

I had similar thoughts.

However the size and shape distribution is unusual..all the tektites in my
collection have very variable shapes. I would have expected to see some more
irregular shapes from melt droplets.


Right, these Martian spheres are remarkably similar in size and shape.
However, dissimilarities between Mars and Earth (not to mention
between different impact events) might account for the differences you
observe. Consider that the paper I cited by R.D. Lorenz

http://www.lpi.usra.edu/meetings/5thMars99/pdf/6039.pdf

notes dissimilarities between microtektite formation on Mars versus on
Earth. For example, on Mars, impacts energetic enough to produce only
2.5-km-diameter craters may produce microtektite while 10 km craters
are necessary on Earth. With more impacts producing microtektites,
Lorenz predicts that microtektites "should therefore be widespread on
Mars." He also observes that: "for Mars, with lower escape velocity
and further from the sun, such velocities are lower than for Earth,
and so spherules are larger." Spherule size is also "limited by
surface tension's ability to overcome aerodynamic stress," and thus
Mars' thinner atmosphere should also affect spherule formation
differentially. These factors suggest that spherules on Mars may be
both more abundant and structurally different than spherules on Earth.




On the "berries" that have been sliced open there dosen't seem to be any
zoning or indeed any kind of structure..the structure is really isotropic.

Correct. In these images from Opportunity we first see some
"blueberries" embedded in rock. Subsequent images show the same
rock after being subject to Opportunity's Rock Abrasion Tool that
reveals a cross-sectional view of the interior of the sphe

http://marsrovers.jpl.nasa.gov/galle...nity_m034.html


Ian Goddard's Journal: http://iangoddard.net/journal.htm

"When we have lived any time, and have been accustomed to
the uniformity of nature, we acquire a general habit, by
which we always transfer the known to the unknown, and
conceive the latter to resemble the former." David Hume