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.

Thursday, September 1, 2011

Possibilities of Wroewolfeite and Leadhillite at Loudville

Our most recent post noted we were eager to follow up upon a recent find of suspected wroewolfeite at its type locality, namely the Manham River Dumps near Loudville, Massachussetts. As noted, the "finder" was the legendary Patrick Haynes, whose micromineralogical acumen has led to the discovery of eight new minerals. He has since photographed through his scope the piece he showed me at the site and also, upon later examination of his day's take, identified a second speck of similarly curious crust. Patrick emailed the two images shown above with the following commentary:

I do not know if the two blue images I sent are wroewolfeite. They could be posnjakite, langite, or ktenasite. The first one is a film/crust alteration product on underlying sphalerite. The more green one is a mass of very fine-grained xls. They could easily be 2 different minerals, but most mineralogists do not want to "waste their time on crusts" so I will probably not ask anyone to ID them.
Langite is the only of the three other possibilities mentioned to have been reported from this locality (at least according to Mindat). In any event, it's an interesting find, especially since we we can rule out malachite, brochantite, or chrysocolla.

The brochantite at left and the malachite at right were among the more eye-catching of the microminerals we collected.
Maureen Campeau collected the brochantite, which was photographed by Rod Lee of Simkev Micromounts. Though her field collecting experience is limited compared to Patrick's, her full-time role in the micromount business at Simkev has resulted in a well-trained eye. Patrick collected the acicular malachite. at right as well as the "ball" of malachite shown below at left. I collected a similar albeit dirt-covered malachite ball, but lacked the kind of cleaning tools to render it photogenic. Blame it on red-green colorblindness, but it was on the only rock I managed to collect to bring home.

On another part that same single rock, the blue material pictured at right, another mystery mineral, presented itself beneath my scope: Patrick checked out the image and suggested the same possibilities for identification as in his earlier comments on the "wroewolfeite?" crusts, adding devilline and linarite to the mix. The crystals did not appear to be acicular enough to be aurichalcite, a fragment of which Patrick collected, which is shown in the photomicrograph at left.

More prevalent, on the Manham dumps are micro wulfenite crystals. Patrick came up with several particularly showy examples, the two most interesting of which appear below at right.

One other specimen of particular interest that turned up later was Patrick's find of the hexagonal colourless micromineral at left. With its morphology ruling out cerussite or anglesite (neither of which we found very much of this year), he's thinking leadhillite. " I'm going to label it as leadhillite," he says, "unless I find a mineralogist who'd like to test it." Assuming a reasonable possibility that this really could be leadhillite, collected in 2011 at the Manham dumps in Loudville, Massachussetts, it should be well worth testing. One can be certain that very few leadhillite specimens from the Manham dumps at Loudville, regardless of how miniscule, are known to exist.

Despite its vast array of spectacular minerals, the Manham dumps could prove far less interesting to many collectors than they did to us. The likelihood is almost nil of turning over hand or cabinet specimens save for a bit of massive galena in quartz, a few quartz crystals, or small dirty looking crusts of pyromorphite. Rather, the Manham dumps are about breaking open and then examining with a loupe the ubiquitous vuggy rocks, which get hammered up enough become smaller every year. Rocks showing evidence of pyromorphite on their surface are often the best bets. Woodlands shade the area to camouflage all but a few patches of sunlight under which to scutinize the spoils through a loupe. However, by East Coast standards on a good day, this can be a spot that approaches paradise for aficianodos of microminerals.