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Mineralogical ClassificationDiscrediting Mineral Species

23rd Apr 2006 19:06 UTCAlan Plante

It seems that we periodically get into discussions about species that probably shouldn't continue to be listed as approved and go around and around about the fact without anything really getting done. But there is a procedure that has been endorsed by the CNMMN of the IMA for discrediting species, which anyone with the wherewithall can make use of. "The discreditation of mineral species" by Peter Dunn, American Mineralogist, v. 75, p. 928-930, 1990, outlines this procedure. Following are highlights from that paper.

The paper starts with a forward which reads:

"The following statement was endorsed by the Commission on New Minerals and Mineral Names, IMA, which has jurisdiction concerning the subject matter and of which the author is the voting member for the United States."

In the "Introduction" Dunn states:

"This paper provides guidelines for the proper discreditation of a mineral species. It should be emphasized from the outset that all discreditations require the approval of the IMA Commission on New Minerals and Mineral Names. Just as a mineral name requires formal international certification before birth and publication, so too does it need a death certificate and a proper burial in the literature."

In "The Literature" section of the paper Dunn states:

"It is very important that the original description be obtained and read in full; reference to abstracts or compendia is insufficient and is frought with potential for further error.

"It is imperative that the original description not only be read, but be understood fully, before discreditation is undertaken."

He notes the difficulties this may ential if the original description was published in a language foreign to the person undertaking to discredit a species, and states that it is the responsibility of that person to deal with these difficulties in as careful a manner as possible.

In the section on "Type Specimens" he states:

"It is imperative that the type material (the same material used in the original description), if it still exists, be utalized in the discreditation of a mineral species. This matter is of paramount importance and cannot be overstated."

He goes on to outline approaches for tracking down type specimens, and also refers readers to Dunn & Mandarino, "Formal definitions of type mineral specimens" American Mineralogist, v. 72, p. 1269-1270 (1987), and Embrey & Hey, Type specimens in mineralogy," The Mineralogical Record, v. 1, p. 102-104 (1970).

Dunn then goes on to state:

"If all these efforts fail, it may well be that there is no type material... If the type material cannot be obtained, it may not be possible to be certain about what material was described, and formal discreditation therefore may be impossible."

But he continues with:

"There are, however, instances where clear, unambiguous type specimens cannot be found, yet much authentic material from the type locality exists in systematic collections."

And he then outlines a more exacting procedure whereby such 'authentic' material can be used in the discreditation process.

Basically, Dunn is saying that every possible effort must be made to track down the type material in order to effect a discreditation - and that if it cannot be found it is going to be much harder to discredit the species using non-type material. Not impossible, but much harder.

In the next section, on "Discreditation", he states:

"In many cases the true identity of the material is established by the investigator on nontype specimens, and this result then prompts the search for type material so as to permit a formal discreditation. When the type specimen is obtained, a few simple tests may serve to confirm earlier findings and provide conclusive proof.

"However, it is best to define the type specimen as well as possible, and to describe it as completely as possible.

"Certain parts of the discreditation procedure are critical; most species are defined on the basis of one or more prime discriminatory factors that serve to give the species unique status. Commonly, the descriminating property will be the chemical composition or crystallographic symmetry. In such cases, that property must be explicitly examined... These factors are paramount, but other aspects should also be investigated."

He goes on to outline the various cases one might come across - mixtures, synthetics, fakes, errors in the original work, etc... The paper is quite thorough in it's coverage. It is also very well written - obviously crafted to be as unambiguous as possible, and to be as helpful as possible to people who wish to tackle specific cases. My hat is off to Dr. Dunn in these respects.

I would like to add the following observations:

The CNMMN is but a handful of people whos' job it is to backstop researchers - see to it that proposals for new species or proposals for dicreditation or redefinition are on the mark before they are approved and published. It is not their job, though, to research all materials - new or old - and propose new species or discreditations and/or redefinitions. That's the job of the many researchers in the field. If a dubious species has not been discredited, it is because no one in the mineralogical community has taken up the challenge and done the work that must be done. It is not because the commission has not done its job.

So, we can discuss dubious species here all we want - but until someone with the wherewithall takes up the challenge offered by any given case, that species will remain "approved." It takes a lot of work to discredit a species - tracking down the original description and the original material probably being the bulk of the job in most cases - but that is what it takes to get the job done.

Regards

Alan

23rd Apr 2006 23:30 UTCJim Ferraiolo

Nice summary, Alan.

Amen.

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