Monday, May 5, 2014

Beware those Rare Franklin, NJ Micromounts

Dick Bostwick (left) and Van King (right) examining tethered photomicromgraphs. 

In Tucson, this past February, in a very well-received  presentation at the annual Friday Micromount Symposium,  Vandall T. (Van) King warned his audience of the strong likelihood that many of the myriad rare microminerals from Franklin and Sterling Hill, New Jersey were not what their labels proclaimed them to be.  As the owner of a small suite including several specimens alleged to be among the rarest of these species, the topic was of particular interest to me. If three specimens in that suite, namely jarosewichite, flinkite, and cahnite were correctly identified, I could be holding what to some very passionate Franklin aficionados would be submillimeter treasure no  larger than the head of a pin.

In fact, subjecting these specimens to the surest means of identification, namely scanning electron microscopy (SEM) and/or x-ray diffraction (XRD) would be to sacrifice them. Some kind of visual confirmation from a sufficiently knowledgeable expert was the best I could hope for. Upon learning that Van, who is currently busy at work authoring and compiling images for a photographic atlas of  the Franklin area's rare minerals, would be shooting photomicrographs the coming weekend  at the New York/New Jersey Gem and Mneral Show in Edison, NJ, I committed myself to be there. He said to look for him at the table hosted by the Franklin/Ogdensburg Mineral Society and the North Jersey Mineralogical Society.

Bearing the mounts proclaiming jarosewichite, cahnite, and flinkite, as well as several other pieces that seemed questionable,  namely  manganoberzeliite, antlerite, and Mg chlorophoenicite, it didn't take me long to find him.  Equipped with scope, camera and computer for shooting tethered stacked  photomicrographs to about 130x, he was  in the company of  Dick Bostwick and other heralded experts on Franklin minerals. They were all eager to provide input, albeit tentative in some instances, as to the identification of my specimens. At first, I was cautiously optimistic when they quickly recognized from their that my mounts were once in the collection of a deceased, but well-remembered and respected collector and photographer --prior to the digital age---of rare Franklin material.

Here is what I learned:

Dick Bostwick peered through the scope at this specimen, labeled as manganberzeliite and proclaimed that the identification could very well be accurate.

Van then did the same with this specimen, which was labeled as chlorophoenicite from Sterling Hill. He was unable to find any evidence of that species.

Soon thereafter, he checked out this piece, labeled as schallerite. His opinion was that rather than schallerite,  it was probably friedelite.

With my "antlerite," the verdict was warmer. Though not an inordinately rare species, antlerite  is said to be very rare at Franklin. Its  submillimeter presence had led me to believe that any conclusive visual identification would be unlikely. Van informed me that the specimen did look like antlerite.*

At left is the specimen about which everyone was  most curious. Though no more than a millimeter in length, its label  noted those three most extreme  rarities: jarosewichite (believed to be the reddish orange  balls), flinkite (the darker material with a brownish cast), and cahnite (the white material). While unable to identify any flinkite, Van took an interest in this specimen, and spent quite a bit of time studying  that reddish orange ball. He concluded that it was caryopilite, an uncommon member of the serpentine group. As for the white "cahnite?" It could be cahnite," he said.  But how could we really tell?

For his atlas, Van, of course,  was focusing on specimens that were confirmed through analysis by SEM and/or XRD. Needless to say, at least to the best of anyone's knowledge, none of my specimens were ever confirmed, For that matter, very few of the rare micromounts in circulation have ever been so confirmed. Of course, with most rare microminerals, a well-informed visual identification is usually sufficent. However, with many of the extreme microscopic rarities, especially  from Franklin/Sterling Hill, it's Caveat Emptor. 

*Prior to publication, I transmitted to Van a draft of this post for an accuracy check. His response included the following quote: 
By the way, we just learned from Lance Kearns that the Sterling Mine "antlerite" we sent for verification is gypsum colored by malachite. Your specimen does look what people have been passing around as antlerite. I would add, in retrospect, I don't know of a valid "antlerite" in private hands if the tested specimen was only gypsum.  The FrOgs (sic Franklin - Ogdenburg mineral aficionados)  will be chirping for a while over the results that just came in.