"Mark Fergerson" wrote in message
news:MFj0c.7437$h23.6664@fed1read06...
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.

Terrestrial tektites get their shapes from aerodynamic
effects, no? Less Martian air, more spherical shape, yes?

Less air and drag means the material might be near to
weightless in flight. There has been some talk about
single small marks on each spherule. Might these be
due to the formation of a trapped bubble as dissolved
gas is released during cooling? The reduced bouyancy
might make it less able to breach the surface which
would also be the first to cool.

George