Conducted by Ron Hartman
Department of Earth Sciences & Astronomy
Mt. San Antonio College
UPDATE ON NWA METEORITE CLASSIFICATIONS
Two posts of interest relating to this series have been received this month. The first is from Bob Verish who commented on the occurrence of free silica in meteorites (mentioned here only briefly last month). He comments:
“Free-silica occurs as a common accessory phase in enstatite chondrites, aubrites and eucrites, and it has also been reported in chondrules and clasts in ordinary, CM and K (Kakangari) chondrites.”
Also, there have been a number of inquiries regarding the classification of NWA (Northwest African) meteorites. The second post is a response from Dr. Jutta Zipfel, representing the Nomenclature Committee of the Meteoritical Society, regarding this issue. She writes:
“I am glad you asked this question because there seems to be large confusion about naming meteorites from NWA. The naming system for meteorites from indeed differs from all other areas.
“In the past meteorites that had well documented (GPS and pictures, etc.) find locations or that were found or observed to fall by private people all got classified (this appears to be still the case); in addition these meteorites were not marketed before they had been classified. Typically the NomCom is informed about the existence of such meteorites by the scientists who did/do the classifications. Therefore provisional names do not really apply for these.
“Meteorites bought in large quantities in Morocco faced us with a new problem. Many of these were not brought to the attention of the scientists or of the Meteoritical Society but were sold to private collectors immediately.
“We introduced the system that dealers can/May ask for provisional names for all meteorites they bought in Morocco. These names are not official but can become official under certain circumstances (see below). We see the advantage in this system that we learn about the existence of even those meteorites that will never get classified but are sold immediately to people outside the scientific community.
“The naming follows these rules:
1) For a basic information submitted we will pass out a provisional NWA number, no classification is needed for this!
The basic info must include:
when and where the meteorites were bought, any information about the possible location of find, total known weight in grams or kg, number of specimens, a guess to its classification (e.g., ordinary chondrite, carbonaceous chondrite, iron, etc), a description (e.g., fusion crust, weathered, fresh etc), name and address of person (this person can also stay anonymous if wished) who holds the main mass.
“2) The basic information (under point 1) and the submission of a classification and the deposition of a proper sized type specimen (20g or 20% whichever is less) will qualify a meteorite for an official name. If the basic info (under point 1) was provided before submission of the classification and the meteorite had already a provisional name this name will be voted on to become the officially approved name. Otherwise a new name will be given.
“The submission of the info listed under 1) of course is voluntary for meteorites that should never become classified. However, we appreciate any cooperation from the dealers’ side to provide such info. We think that it is important to get an estimate of the number of meteorites coming out from Morocco and neighboring countries.
“Since we do not expect that all meteorites that received a provisional NWA name will be classified, we insist on the basic information before handing out any provisional numbers – we had to learn that it becomes very difficult to receive the basic info afterwards.”
My thanks to Dr. Zipfel and the NomCom. We all need to realize that Committee members offer their efforts as a service to all of us (dealers and collectors as well as the research community) and that they are quite overburdened with the extra work they are encountering with the large number of meteorites now being found.