New find - 3 colors longwave scapolite, prehnite and calcite, from Quebec, Canada

During an exploration trip with one of my partners on April 30 2022, in the area of Saint-Michel-De-Wentworth, north-east of Grenville-Sur-La-Rouge, Quebec, Canada, I found some really nice scapolite with an unknown mineral which fluoresces blue under longwave UV. The scapolite fluoresces bright yellow under longwave UV (not as bright as "wernerite", but maybe about 60% as bright - still very bright), and the blue fluorescing mineral is a bit dimmer but still decently bright. I had samples sent to George Adleman, for identifying the blue fluorescing mineral via Raman spectroscopy; it turns out to be prehnite. Not a rare mineral per se, but blue fluorescing prehnite seems to be quite uncommon. So the 2022 collecting season began on a pretty exciting note! Some specimens, like the one shown in this post, also show patches of greenish fluorescing and phosphorescent calcite (ID also confirmed by Mr Adleman). The color of the calcite is more greenish in person - pretty hard to photograph. For some reason, my camera usually "sees" the calcite light blue instead of greenish. When seen in person, it's easier to qualify this specimen as a 3 colors LW fluorescent, since the calcite contrasts better with the prehnite in person.



The brightest response is definitely under longwave UV; but the midwave UV response is quite decent too - bright enough for a well-lit display. The brightness of the specimen in the midwave UV pictures below show how bright it fluoresces about 12-15" away from my 48W midwave transilluminator. Apart from the blue fluorescing prehnite, this material has a pretty cool characteristic: it fluoresces differently under standard midwave UV tubes (302, 306 or 311 nm), and the new midwave UV LEDs (310 nm). This difference is obviously due to the fact that the new MW LEDs emit most of their output in the 310 nm UV-B range, while the output of standard tubes (both midwave and shortwave) is much broader, and some UV-A (longwave UV) light is also produced. Minerals that are highly reactive to UV-A, like some scapolite and sodalite, will react differently under the pure UV-B output of the new MW LEDs, than under the broader spectrum of the older mercury arc tubes.



Even if the fluorescence of this material is quite weak under shortwave, and not very bright under midwave, in my opinion it's just bright enough to make this material qualify as a "multi-wave" fluorescent. Under 310 nm midwave LEDs, the scapolite shows attractive greenish tones, along with oranges, browns and yellows; under standard MW tubes, the greenish tones are much weaker, and the oranges and yellows dominate. Under shortwave UV (both tubes and LEDs), some of the areas that show greenish under midwave shift to reddish tones, and lots of dull oranges and yellows are seen. Shortwave gives the weakest response. In the specimen shown in this post, some very bright blueish dots of [diopside?] are seen under shortwave. The scapolite sometimes shows some dim fluorescence under 450 nm blue light (not shown).



Shown in the gallery below is one of my favorite specimens; it is shown, respectively, under longwave, then under 310 nm MW LEDs, then 302 nm standard MW tubes, shortwave (254 nm tube), and lastly, in visible light.


Size: 22 cm X 15,5 cm X 7,4 cm




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