This unimposing specimen actually has several very unusual and interesting features, not the least of which is verified columbite-(Fe) – a very rare mineral at MSH. Caveat: Only qulaitative EDS was used. While the Fe peak looks "substantially" higher than the Mn peak, comparison of peak heights is risky for such scans. Also, while two out of three samples from this find showed Fe > Mn, a third sample showed Mn > Fe.
In addition to the columbite, there are two good sized gobbinsite aggregates, several “rosettes” of gmelinite-Na (some possibly altered), and complex, flattened, crystals of siderite inter-layered with muscovite, some of it in the form of octahedral stacks, mostly with hollow interiors. Presumably the latter are PSM. (See the “Analysis” tab for some of the scans.) Bottom line: This is a most unusual specimen from the famous Poudrette pegmatite.
The first photo (FOV 2.2 x 2.1 mm) shows the broken columbite crystal ( max diameter 0.9 mm) that was analyzed. Another analyzed specimen from this find had complete, free-satnding, euhedral crystals of columbite, but it seems that many, if not most, columbite crystals at MSH are embedded and thus unlikely to survive exposure.
The second photo (FOV 2.5 x 1.65 mm) shows the other, partial, columbite crystal (0.85 mm). This one was not analyzed – it’s not practical to analyze everything!
The third photo(FOV 3.6 x 2.5 mm) shows one of the gobbinsite aggregates (2.5 mm) and a somewhat altered looking rosette of gmelinite-Na (2.1mm).
The next pair of photos (FOV 4.55 x 5.65 mm) shows some of the flattened siderite crystal, the other gobbinsite aggregate (2.3 mm) and some of the yellowish/tan muscovite. Note especially the muscovite “octahedron” (0.75 mm) at bottom center. There are several others on the specimen. (This is the most distinctly octhaderal looking one.)
The next pair of photos (FOV 4.5 x 5.8 mm) shows another altered gmelinite rostette (top right) along with strangely inter-layered siderite and muscovite. I’m not sure if the roughly circular object at bottom left is another hollow muscovite PSM or a ‘bottom”view of more of the altering gmelinite.
The last pair of close-up photos (FOV 4.3 x 6.7 mm) shows more of the inter-layered siderite and muscovite. The siderite crystal attop center is 1.9 mm wide.
There is also some pyrite on the specimen. Some other specimens from this find have chalcopyrite (rare at MSH), but EDS for this specimen showed pyrite for the analyzed speck..
Single item shipping weight (with TN case) is 3.3 oz (92 g). For shipments outside the USA, up to a total weight < 8 oz (225g), this can be combined with items from this or other auctions for the same postage.
Within the USA, postage now varies by destination. For total weights up to 13 oz, it ranges from $4.50 to $7.00 (including packing etc). Above 13 oz (up to 16 oz), I will use “own box” Priority Mail. The rate, including packing, varies from $8 to $10.