Hi Bob -
Right off, I'd have to say that I concur with you generally on an asteroid source for irons. The problem is that we do not know the composition of the centers of comets. (And Hoba does lack an impact crater, indicating a low velocity of impact.) We do not know the composition and distribution of the original accretion dust disk, nor do we know the effects of gravitational precipitation over billions of years What is also "interesting" is the assertion that all of these "possible" astroblemes are the result of come impact. I do not know what the distribution of asteroids on the plane of the solar system is. In any case, all of these hypothesized astroblemes would have to be under 200 million years old, if I remember the tectonic re-surfacing of the Earth correctly. PS - I also "remember" that when I started off on this, McSween's estimate of the number of parent bodies was accepted. It is now down to 5 patent bodies if I recall correctly. Steve Garica has raised an excellent point about the requirements for the formation of peridote, and what this implies for the parent bodies. Right now I am more concerned with Brenham artifacts here in Ohio. E.P., Interesting stuff but I believe he's a bit off by calling the huge Hoba iron-nickel meteorite (and other Hoba-like material he believes is nearby) fragments from a comet. This stuff comes from asteroids. Thanks, Bob ______________________________________________ Visit the Archives at http://www.meteorite-list-archives.com Meteorite-list mailing list Meteorite-list@meteoritecentral.com https://pairlist3.pair.net/mailman/listinfo/meteorite-list
