This question periodically comes up, and the answer is: there isn't one.
The fact of the matter is that there is no "official" way of classifying meteorites (i.e., endorsed by a professional society or journal or other group). When it comes to publishing classifications, it is up to the authors and, ultimately, editors to decide what to do.
The nearest thing to an "official" classification is what you see in the Meteoritical Bulletin. But this only looks official. Their Nomenclature Committee's (nomcom's) primary jurisdiction is only over meteorite names. Their classifications are simply a matter of their own editorial policy.
The prevailing tradition on the nomcom is, however, a sensible one. They normally publish classifications that are consistent with common usage among scientists. They are normally conservative, meaning that they don't publish a new type of classification until it is obvious that at least a good part of the community has bought into it. They also mostly do not publish unusual classifications without reasonable evidence to support it. They use the literature as a guide to what criteria are necessary to demonstrate a given classification. There is usually enough expertise on the nomcom to do this by inspection or with a little reading. However, mistakes, oversights, and misjudgments can and do happen in this system, especially at the fringes of "common usage."
As for the general scheme used, check out the Wikipedia Meteorite Classification page, which I largely wrote. http://en.wikipedia.org/wiki/Meteorite_classification. For any given group, I may be able to give some insight into what criteria the nomcom has traditionally looked for. The two main references cited there (numbers 2 and 3) are both good classification papers that give a lot of details on the properties of the various groups. Unfortunately, both are chapters in expensive books, but pdf reprints can probably be obtained from the authors.
Jeff At 04:16 PM 6/22/2008, Mr EMan wrote:
The geek in me has always been curious as to the actual classification criteria that a researcher uses to make classification. Does anyone have them by name or PDF or hard copy? Or volunteer to explain the general scheme for different classes? Sounds like fodder for a met-times exposeË. Elton ______________________________________________ http://www.meteoritecentral.com Meteorite-list mailing list Meteorite-list@meteoritecentral.com http://six.pairlist.net/mailman/listinfo/meteorite-list
Dr. Jeffrey N. Grossman phone: (703) 648-6184 US Geological Survey fax: (703) 648-6383 954 National Center Reston, VA 20192, USA ______________________________________________ http://www.meteoritecentral.com Meteorite-list mailing list Meteorite-list@meteoritecentral.com http://six.pairlist.net/mailman/listinfo/meteorite-list
