Saturday, August 22, 2009

Manhan Lead Mine Dumps: A Myopic Perspective

As an unseasoned and inexperienced field collector, the story here to unfold amazes me more than any other mineral collecting experience of my life. It's all about the booty I managed to uncover within the course of but an hour on August 6, 2009, by sifting through surface material at the Manhan Lead Mine Dumps near Loudville, Massachussets. Having forgotten my loupe and equipped with but with a small hammer, my odds of getting lucky were further restricted by having to collect on my knees in just a couple little spots thanks to a condition for which my right hip was totally replaced this past Tuesday. Furthermore, the entire space available for collecting covers no more than a few hundred square feet scattered with rocks tracing to a 17th Century operation. For decades, if not centuries, the gospel has emphasized how necessary it is for one to dig deep. As an aficionado of micro minerals, I beg to differ.

Photographed at about 30x, the image beneath our title is little more than a couple millimeters across the inside of a little quartz rock I split open with my hammer. The linarite, wulfenite, and pyromorphite should be obvious enough for all to observe. Look more closely or blow up the image further, and there's evidence of a light emerald green colored mineral and a hint of something the hue of turquoise. According to a 1983 article that was published in 1999 by the Triassic Valley Bulletin, I would speculate that the light green material is brochantite. "Anything the color of turquoise, I would guess is probably aurichalcite, although it's fun to stretch the old imagination a bit in the direction of caledonite or wroewolfeite, both of which the above referenced paper acknowledges to be present here. For that matter, Loudville is the type locality for wroewolfeite.

No farther-fetched would be my speculation that the image at left could be micro plumbogummite. The same article stated that this rare hydrous lead aluminum phosphate had been reported here in 1981. Its resemblance to a micro photograph by Peter Cristofono that appears on MINDAT of plumbogummite from Loudville is my frame of reference, albeit a long shot.

A more certain if less remarkable find yielded up by the dump surface were the white blocks of barite shown at right. Regarding a more confident identifcation, I'm once again indebted to Peter Cristofono for the photograph of Loudville barite he submitted to Mindat, which is shown at right.

I confess to reservations about tooting my horn over all this and am well aware that plenty of my speculation could be subject to question if not scoffed at. The rationale, instead, is to make a pitch on behalf of how much more fun the pursuit of microminerals can render the collecting game to be. For sure, I wouldn't dare to dream of coming up with a cabinet specimen at this spot beyond perhaps the likes of some mediocre massive galena and sphalerite or weathered pyromorphite. The pyromorphite was rather common, usually in the form of a dull light brownish green crust. Often it was associated with rocks with vuggy surfaces that I busted up and then placed the least boring looking chunks into my knapsack. I had little expectation that any of them would ultimately prove to be interesting.

What a wonderful surprise to get home and peer at just a few of these pieces under my scope. I collected about five pounds worth, of which thus far, I've checked out about a pound, so there's plenty left in my knapsack.

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