Shown here is a very nice specimen of super deeply tenebrescent sodalite var. hackmanite, from the Mogok Township, Pyin-Oo-Lwin District, Mandalay Region, Myanmar.
Hackmanite from Myanmar is incredibly hard to find nowadays, especially as rough, uncut mineral specimens; also, it's usually very expensive. So, for this reason alone, I highly treasure this specimen, which I consider myself very lucky to have in my collection. But what also makes it very valuable, is how deeply tenebrescent it is; it changes color upon exposure to all UV wavelengths, very quickly. And also, the fact that quite a generous amount of the rare mineral johachidolite is associated with it. Yellow fluorescing scapolite is also present. Some feldspar (adularia) associated with those minerals fluoresces light blue under longwave UV; it could be assumed that the blue is visible light being reflected from the UV source, but it is actual fluorescence, which I confirmed by placing a piece of UV blocking polycarbonate between the UV light and the specimen. Interestingly, the hackmanite shows small areas of drastically increased fluorescence around grains of uranothorianite.
Another aspect I really like about this specimen, is how it reacts drastically differently under each UV light sources (not only longwave, midwave and shortwave, but also under tubes vs LEDs).
Under longwave UV, the hackmanite fluoresces bright orange; the scapolite fluoresces bright yellow, the adularia fluoresces light blue. Under midwave UV, the hackmanite switches to blue, white, yellowish and reddish hues. Comparable colors show up under shortwave, with some differences.
Shown in the gallery below, respectively: Longwave UV, Midwave UV (306 nm tubes), Midwave UV (310 nm LED), Shortwave UV (254 nm tube), Shortwave UV (255 nm LED), SW phosphorescence, MW phosph., LW phosph., SW tenebrescence, LW tenebrescence, Natural color. The reverse side of the specimen is shown in the same order in a second gallery below.
Size: 7,8 cm X 6,1 cm X 3,3 cm, 121 grams
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