Thursday, September 22, 2011

My Wheatleyite

Our post of August 21, 2011, about the East Coast Show at West Springfield, Massachussetts, heralded what is pictured above as follows:

My most expensive purchase was a speck of something visually indiscernible inside a clear plastic capsule. That evening, one of the most prolific micromount dealers on the planet, namely Maureen (Campeau), spent nearly five minutes examining the capsule under the scope to ascertain that it was not in fact empty. So much for my stewardship of one of the rarest species in existence (from Phoenixville, PA), which will be the subject of an upcoming post. Stay tuned.
The visually indiscernible speck---at least to the naked eye---in that plastic tube turned out to actually be several similarly indiscernible specks, three of which appear to bear the mineral wheatleyite. The species is a natural sodium copper salt of oxalic acid, named from the long closed and inaccessible Wheatley Mine in Phoenixville, Pennsylvania. In our image, wheatleyite is apparent in the blue staining on the dark pieces on the right (probably sphalerite) and the clear crystal just above and to the left of the larger colourless speck (possibly anglesite.)

The renowned collector Bill Pinch discovered wheatleyite on the Wheatley dumps in the form of a few micro-crystals on a rock. He provided a portion of what was to become the type (and only) specimen to the Smithsonian. There, the now legendary mineralogist Pete Dunn shepherded the material to approval and ultimately publication through The American Mineralogist in 1986. The article refers to Bill Pinch's find as "the type (and only )specimen of wheatleyite." It goes further to note that the piece "is known from only one hand specimen, which consists mostly of massive galena and sphalerite in contact with quartz."

The Handbook of Mineralogy refers to wheatleyite as "very rare, on a specimen found on the mine dumps of a Pb–Zn vein deposit." The only reference to the possibility that another specimen might exist was an uncited mention in Bernard and Hrysl's Minerals and Their Localities of an occurrence at the Nishinomaki Mine in Japan. Such an occurence is not noted at MINDAT or elsewhere that my own extensive search in cyberspace could locate.

Needless to say, there is not much Wheatleyite around. The well-known and respected species dealer from whom I acquired my wheatleyite specks noted that his source had been a "tiny vial of fragments" that Bill Pinch "gave, sold, or traded" to the late species collector, Joseph Cilen. from whose 23,000 specimen collection he purchased it.

Since the West Springfield show, I managed to acquire another speck of wheatleyite, this time in a vial from the same dealer. He informed that it was the one additional grain he could provide. Pictured at left, this new piece resembles the sole picture that I could find on MINDAT (as well as anywhere else), although the blue colouration is minimal.

So now, in my collection, are several specks of what surely has to be one of the rarest species in the mineral kingdom. What I paid for them will remain private. It should be enough to say they went for hundreds of times the price of gold.

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