Synchysite-(Ce) as a replacement of petersenite-(Ce) and/or rémondite-(Ce) is fairly abundant in the hydrothermally altered pegmatites at MSH, but it is fairly rare otherwise. This specimen features exceptionally good crystals of synchysite-(Ce) (probably from an “ordinary” altered pegmatite).
The first pair of photos (FOV 3.4 x 2.5 mm) shows one of the main clusters of synchysite crystals. The crystals are similar to, but not as large as, the ones shown in Figure 142 of the Mineralogical Record, Vol 21, pp 284-359. More commonly, synchysite-(Ce) at MSH occurs in the form of “rosettes”.
The second pair of photos (FOV 2.1 x 1.4 mm) is a close-up of some of these same crystals. The crystal on top is 1 mm in diameter
The third pair of photos (FOV 3.4 x 2.1 mm) shows two relatively isolated synchysite-(Ce) crystals to 1.25 mm.
The fourth pair of photos (FOV 5.35 x 2.75 mm) shows yet more synchysite crystals at lower magnification.
There are a few other clusters of similar synchysite crystals on the specimen.
In addition to the synchysite-(Ce), the specimen hosts small calcite crystals, some of which have very peculiar morphology, or so it seemed to me. In fact, at first I mistook then for unusual untwined crystals of eudidymite. Fortunately I had enough presence of mind to dunk a couple of them in HCl – they fizz like mad. I decided not to post any close-up photos of these. Perhaps a minor curiosity, but not very exciting. You can (sort of) see them in the full view photos.
In the first full-view photo, the calcite is the lighter colored band running roughly horizontally in the center. The synchysite is best seen in the lower right corner. The background is a pale tan carbonate (probably dolomite), which sits on darker olive green siderite and white albite.
The second full-view photo shows another side of the specimen. More synchysite can be discerned at top right. Below it is more calcite.
Single item shipping weight (no case) is 3.4 oz (88 g). For shipments outside the USA, up to a total weight < 8 oz (225g), this can be combined with other items from this or other auctions for the same postage.
Within the USA, postage for total weights up to 13 oz ranges from $4.25 to $6.50 (including packing etc) regardless of destination. Above 13 oz, I will use “own box” Priority Mail. The rate, including packing, varies by destination from $7.25 to $9.50.