Hisingerite is “medium-rare” in altered pegmatites at  MSH. On this specimen, the hisingerite and “other stuff” form partial pseudomorphs probably after aegirine. The specimen is unusual in that some of the grooves and cavities in the hisingerite harbor greenish flaky stuff that looks like ferroceladonite. And in fact, similar material from another find was confirmed (at the ROM in Toronto) as hisingerite with ferroceladonite. However, in this case, an EDS scan for the presumed “ferroceladonite” was actually a slightly better match for “hisingerite” than the scan for the  hisingerite itself! Go figure. See the “Analysis” tab. For more details, see after the photo descriptions.

The first (full-view) photo should make it clear that these are PSMs after a long-prismatic precursor.

The next two photos (FOV 4.7 x 5.9 mm) show the typical resinous appearance and conchoidal fracture of the hisingerite.

The last photo (FOV 3.8 x 2.5 mm) is a close-up of one of the areas with the green flaky/fuzzy stuff.

Details regarding the IDs: Hisingerite is Fe3+2(Si2O5)(OH)4 · 2H2O, Ferroceladonite is K(Fe2+,Mg)(Fe3+,Al)(Si4O10)(OH)2. It is “strictly illegitimate” to compare peak heights qua quantitatively on qualitative EDS scans such as these. Nonetheless, based on previous results for “known” minerals, I have observed that, all other conditions being the same, the equipment is roughly twice as sensitive to Fe than to Si, and even somewhat more sensitive to K. On that basis, I would expect a scan for ferroceladonite to have roughly equal Si and Fe peak heights, whereas for hisingerite I would expect the Si peak to be about half as high as the Fe peak. In addition, I would expect a fairly prominent K peak for ferroceladonite. I have included scan #284 for ferroceladonite from another specimen which looks much like what I would expect. But scans #314 and #317 for this specimen both look like what I would expect for hisingerite. In particular, there is very little K.  Ironically, scan #317 for the little fuzzy green flakes appears to be the better match for hisingerite. What does that mean? I don’t know. In any case, based on the physical appearance, mode of occurrence, and the EDS scan, the brown resinous stuff is almost certainly hisingerite. Note: Hisingerite is often poorly crystallized. XRD can produce useless or even misleading results.

Single item shipping weight 3.7 oz (105 g) . For shipments outside the USA, up to a total weight of 8 oz (225 g), this could be combined with other items from this or future auctions for the same postage. If you wish to keep an “open box”, let me know.

For shipments within the USA, there is a nominal increase of about $0.20 for each additional ounce. Above 13 oz I will use “own box” Priority Mai. The rate (including packing) is ca $9.25 (varies by destination).