Changes In Mineralogical Nomenclature: Varieties
by Alan R. Plante, Gorham, NH.
A recent discussion about mineral nomenclature on a mineralogical eBB brought me an email from a friend asking about the IMA definition of a "variety." My answer, in a nutshell, was: "The IMA doesn't define 'variety' - in fact the IMA is trying to kill the concept in scientific literature."
"IMA" stands for the "International Mineralogical Association," which is the professional association that regulates mineral names and related terms within the professional mineralogical community. It is a commission of the IMA which reviews proposals for new mineral species and their names. (This commission used to be called the "Commission on New Minerals and Mineral Names" (CNMMN), but just this past summer - 2006 - that group and the "Commission on Classification of Minerals" (CCM) merged to form a new commission: "Commission on New Minerals, Nomenclature and Classification" (CNMNC).) The original CNMMN was established in 1959 - shortly after the IMA itself was established. In short, a newly proposed mineral species and name are not considered to be scientifically "valid" unless the IMA’s commission says it is.
My friend was floored to learn that there is no current official definition of "variety." Based on my talks and correspondence with other collectors, she was hardly alone in her belief that "variety" is a valid term with scientific relevance in modern mineralogy. There is quite a bit of confusion outside the professional community regarding this issue.
In order to understand the current IMA stance it is necessary to look at the issue from a historical perspective. It was during the late 1700s and early 1800s - when modern chemistry and physics were being developed and spreading around the globe - that mineralogists came up with the concept that variations of a mineral species could be distinguished and given names - varietal names - as a shorthand way of noting these distinctions. They recognized that there were three types of distinctions: 1) morphological (shape), 2) chemical, and 3) optical (eg. color). Using this concept they coined or borrowed names such as "selenite" (for water-clear crystals of gypsum), "chalcedony" (for the form of quartz that is composed of matted SiO2 fibers), "aquamarine" (for blue-green gem quality beryl), "manganapatite" (for Mn2+-rich apatite,) and so on - for literally hundreds upon hundreds of variations of a great many mineral species (as they were defined back then.)
By the end of the 1800s two things had happened. First, so many varietal names had entered the lexicon of mineralogy that it was becoming difficult to remember them all and know what they referred to. Second, the leisure class was growing in numbers by leaps and bounds as more and more people had time and money to spend on pursuits other than survival - and more and more of these people were "dabbling" in things such as nature studies and the arts - including mineral collecting and the lapidary arts. These people were scurrying about the globe (or at least that bit of it within their reach...) - and they were finding all sorts of new and interesting things. Among these finds were many distinctive mineral materials, both species and varieties of species - even whole new "Groups" or "Families" of them. And they were giving these new finds names. Many of the names they came up with were actually localized nicknames (eg. "Herkimer Diamond," "Pecos Diamond," "Cape May Diamond"), but they treated them like they were varietal names - and even the mineralogists of the time treated many of them as such, without regards for the consequences this might have down the road. So as the early 1900s unfolded the professional community found itself dealing with a morass of mineral names - many of which had little or no scientific value.
For the first half of the 1900s efforts were made to get a grip on mineral names - to make sense of them and present them in an organized way. And a large part of this effort was spent trying to sort out varietal names and make it clear that they were varietal names - not species names. Thus "selenite" became more frequently seen in the scientific literature as "gypsum var. selenite," and "chalcedony" was presented as "quartz var. chalcedony," and on and on... Also, advances in the science throughout the 1800s and early 1900s were refining the definition of what constitutes a mineral species - and in quite a few cases it was determined that what had previously been thought to be a single species actually encompassed materials that included two or more species. (The reverse also happened, where two or more materials thought to be separate species were actually found to be variations of a single species.)
A good example of this is the case of "apatite." During the mid to late 1800s apatite was considered to be a valid species with a number of chemical and morphological varieties. Among these varieties were "carbonationapatite," "fluorianapatite," "hydroxylationapatite," "strontianapatite" and "manganapatite". Then in the early 1900s our understanding of crystal structure and the role cations and anions play in them caused a change in the definition of a mineral species - and this resulted in "apatite" being broken out into the species "fluorapatite," "chlorapatite." "hydroxylapatite," "carbonate-fluorapatite," and "carbonate-hydroxylapatite" (based on the predominant anions). But "strontianapatite" and "manganapatite" remained varietal names because the Sr and Mn they noted were not present in sufficient quantities in the structure to warrant being given species status. The problem was that these varietal names could be applied to more than one of the newly defined Apatite Group species - you could have an Sr-rich fluorapatite or hydroxylapatie, or either of them might be Mn-rich. And since names such as "fluorapatite var. manganaptite" would be cumbersome and somewhat redundant, the decision was made to replace them with simply "flourapatite v. strontian" and "flourapatite v. manganoan" - using chemical adjectives as varietal names. In the process names such as "strontianapatite" and "manganaptite" were rendered obsolete - after all, there was no longer a mineral named "apatite" that the chemical adjectives could be tacked onto. If you thumb through a copy of "Dana's System of Mineralogy, 7th Edition" you will find hundreds of examples of where chemical adjectives are used following the species name and a "v." The two main volumes of this edition were published in the 1940s and early '50s, and constitute perhaps the single best example of what the science tried to do in order to get a handle on varietal names.
Alas, while they were able to get a grip on chemical varieties, things did not go so well with morphological and optical varieties. More often than not, the varietal names for these types of varieties did not impart scientific knowledge to begin with. For example. "tremolite v. byssolite" does not tell you the varietal name refers to a fibrous form of the mineral. You have to learn that this is what "byssolite" means. Similarly, "gypsum v. selenite" does not tell you what the "selenite" means - that it refers to water-clear crystals of gypsum (as opposed to other forms, such as "alabaster.") In the end, it is mostly the color names - "amethyst," "aquamarine," etc. - that are clear in meaning on their own. Most of the other names aren't. So they still had a problem.
Added to this, more and more hobby collectors and lapidary artisans were arriving on the scene - finding more and more things and tagging them with more and more nicknames - which they promptly decided were perfectly serviceable as "varietal names" without thinking about it from a scientific perspective.
Things were actually getting worse - not better...
Finally, throughout the early half of the 1900s there was a growing number of professionals who felt that the varietal concept had gotten so far afield from the science as to render it useless - that there were so many ambiguous terms and terms without scientific meaning in use, and still being coined, that it had become futile to try to do anything about it. They recommended simply abandoning the "variety" level of mineralogical classification. By the time the CNMMN was established in 1959 the number of professionals who felt this way were in the majority; so the commission simply didn't include "varieties" in their mission statement. In fact, they began a campaign to suppress the use of varietal names in scientific papers and books, strongly urging professionals to not use them, and to not coin new ones.
One of the first steps they took was to convert the chemical adjectives - "strontian," "manganoan," etc... - back into simply being descriptive adjectives once again. "Fluorapatite v. manganoan" became "manganoan fluorapatite" - with it understood (by professionals, at least) that "manganoan" was just a way of noting that the fluorapatite specimen in question had some unspecified amount of Mn2+ in it. It was not to be construed as indicating a "variety" existed. There was, unfortunately, some confusion generated by this move. There are names of species which have chemical adjectives incorporated in them (eg. "carbonate-fluorapatite"). While the CNMMN made it clear that if the chemical adjective was connected by a hyphen to the rest of the name it meant a species - while unconnected adjectives didn't - it didn't always work.
Cases of usages such as "carboante fluorapatite" occurred - the hyphen being omitted. There was even some debate about old species name in which the hyphen was not used: Some felt they should stay that way, some felt the hyphen needed to be added to make it clear. Also, the recommended adjectival modifiers were not really adequate for describing all possible valances - those elements with a single ionic valance state, and those with more than two, could not be accommodated. All-in-all, the measure helped some, but it didn't really solve the problem. - And there were still all those pesky morphological and optical varietal names "out there" (not to mention all the nicknames being used as varietal names) adding further confusion to the nomenclature of minerals...
More recently - just last year (2005) - the IMA changed to a new approach. Chemical adjectives are no longer recommended for use in scientific papers and books. The new recommendation is to use terms such as "Mn2+-bearing" fluorapatite, "Sr2+-rich" fluorapatite, and so on. Which certainly eliminates the problem of whether or not the terms are part of a valid species' name or not. No one should mistake "Co2+-rich" calcite as meaning there is a species called "cobaltoan-calcite." (There isn't...) It's pretty clear the phrase simply indicates a sample of the mineral calcite which happens to contain some cobalt. Also, any valance state can be clearly accommodated by simply stating it using the appropriate superscript with plus or minus sign. This approach may even stand a reasonably good chance of succeeding to clarify things so far as chemical variations go.
But there are still all those morphological and optical varietal names out there - not to mention all those nicknames that are routinely used as varietal names.
The issue certainly isn't resolved - even within the professional community, let alone outside of it.
By now more than a few of the people reading this are chaffing at the bit - they want to know if this means that they should not use varietal names any longer. The answer is NO! It doesn't mean that at all. - Not unless you feel some strong urge to be "politically correct." The fact is that what the IMA is doing is an internal thing - geared to help the professional community deal with things mineralogical in as rigorous a fashion as they can. The IMA has no control over - and probably doesn't want any control over - how the hobby sector uses mineral names. While members of the professional community might wistfully wish that non-scientists would learn scientific nomenclature concerns and adhere closer to scientific principles (and the few of the more militant people might try to get others to "toe the party line") the fact is we are welcome to do as we please.
Varietal names and nicknames are handy ways for us to describe the many nuances we see - or which tests reveal - in minerals. They provide us with a shorthand which makes discussion of minerals easier. And, quite frankly, many of us - most - could care less about the "scientific value" of mineral names. We just want to be able to talk about their differences in a way that we can understand - even if it is simply by mutual agreement about what terms mean. It works for us.
But at the same time we should be aware that our use of varietal names and nicknames is outside the ken of science. Varietal names no longer have the stamp of scientific value they once had - and nicknames never did.
It is as simple as that...
|Bayliss, P., et.al., 2005, The use of chemical-element adjectival modifiers in mineral nomenclature, The Canadian Mineralogist, V. 43, pp. 1429-1433.
|Dana, E.S., 1892, System of Mineralogy, 6th Edition, John Wiley & Sons, New York.
|Ford, W., 1932, Dana’s Textbook of Mineralogy, 4th Edition, John Wiley & Sons, New York.
|Gaines, R. V., et.al., 1997, Dana’s New Mineralogy, 8th Edition, John Wiley & Sons, NY.
|Nickel, E. H., 1995, The definition of a mineral, The Canadian Mineralogist, V. 33, pp 689-690
|Nickel, E. H., & Grice, J. D., 1998, The IMA Commission on New Minerals and Mineral Names: Procedures and guidelines on mineral nomenclature, The Canadian Mineralogist, V. 36.
|Nickel, E. H., & Mandarino, J. A., 1987, Procedures involving the IMA Commission on New Minerals and Mineral Names, and guidelines on mineral nomenclature, The Canadian Mineralogist, V. 25,. pp 353-377.
|Palache, C., et.al., 1944, Dana’s System of Mineralogy, Vol. 1, 7th Edition, John Wiley & Sons, New York.
|Palache, C., et.al., 1951, Dana’s System of Mineralogy, Vol. 2, 7th Edition, John Wiley & Sons, New York.
Copyright © 2006 by Alan R. Plante. Not to be used or stored by any means without my written permission.
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