[meteorite-list] Angular clast composition?

[Jamie Stephens]

Folks,

When I recently started cutting an NWA, I found this angular
clast:

   http://f2.pg.photos.yahoo.com/ph/jhsmorph/album?.dir=/5c68

The background is a 1cm grid.  I cut with oil, and the slice
has soaked a bit in alcohol.

With a 10x loupe, I can't make out any chondrules, but I can
see very fine fracture-like lines.  There are a few bits of
iron in the clast, and it looks like each has rusted some
-- before cutting I think.  I'll sand the slice in the next
day or two.

What's this clast made of, and why is it angular?  Oh, and how
did it get there?

Thanks in advance for comments.

--Jamie