This is a lot consisting of two very different specimens of “donnayite”. They are both from analyzed finds (see the “Analysis” tab).
It is impossible to visually distinguish donnayite-(Y), mckelveyite-(Y) and ewaldite at MSH. It can be impossible even with EDS because the species are often intergrown with each other and with synchysite-(Ce). (In addition, there are some “UK” members of this group.) For one of the specimens, donnayite-(Y) partly replaced by or mixed with FeSO4 and pyrite, is a likely enough ID, so that the label will reflect that. (The dimensions given are for this specimen.)
For the other specimen (which is 2 x 3 x 2 cm in size), XRD (on another sample) said "donnayite group", and a quick and dirty EDS scan confirms donnayite-(Y) with significant Ba. (See the "Analysis" tab.) This specimen is actually the more interesting of the two, because the “donnayite” fluoresces – something that has not been “officially” reported for any member of the group. The yellowish fluorescence isn’t very bright – but it’s clearly there. (But this isn't a fluoresecent dispaly piece by any means!)
The first pair of photos shows the better of the two “donnayite” crystals (or aggregates) on this specimen. It looks like a small (1.7 mm), yellow, pine cone. The next photo shows this entire specimen. The matrix is microcline and analcime sprinkled with natrolite/gonnardite. (I’m not sure what the lustrous brownish cystal is that the “donnayite” is attached to. Maybe just calcite.)
The second specimen (1.5 x 2.5 z 1.7 cm) features blue-gray donnayite-(Y) with Fe and S - perhaps as FeSO4 . (See the “Analysis” tab.) It is typical at MSH for donnayite to be sprinkled with and to include pyrite. It isn't clear just from EDS whether any or all of the Fe and S is coming from such pyrite, or if (at least some of) the pyrite has altered to an FeSO4 mineral. There is certainly plenty of pyrite left that could have been mixed in. There are also tiny purple fluorite cubes (some zoned) on dolomite. The next three photos are for this specimen.
FOV in the first close-up is 6.0 x 3.8 mm. The longest “donnayite” is 1 1/4 mm. FOV in the second close-up is 5.8 x 4.1 mm. The third photo is a full-view showing also associated dolomite and smoky quartz. Found 6/97 in a hornfels seam near the famous Poudrette pegmatite.
Combined shipping weight 3.3 oz. Outside the USA, the stated postage and packing rate applies up to a total weight of 8 oz (225 g).
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