• Frédéric Messier Leroux

Gemmy "Terlingua-type" calcite with blue light and green laser fluorescence

Shown here is a pretty small but nicely transparent, gemmy cleavage rhomb of "Terlingua-type" calcite from the Challenger Cave, Nuevo Leon, Mexico. Like other specimens of that material, not only does it react to all UV wavelengths, fluorescing a different color under each, but also to blue light (450 nm), violet/blue lasers (405 nm), green lasers and green light (530 nm). Since this specimen has a nice transparency, it is an ideal candidate for photographing its response to laser beams, which I didn't photograph in my previously posted specimen from the same locale, which is not gemmy like this one.

Under 365 nm longwave UV, it fluoresces the typical bright bubblegum pink of "Terlingua-type" calcites; the midwave UV (306 nm) response is white, and the fluorescence under shortwave UV is the typical bright blue with intense, long-lasting blue phosphorescence. The green light and green laser response is orange-red, the violet/blue laser (405 nm) fluorescence is greenish yellow, and the blue light (450 nm) response is bright yellow.

In the case of this specimen, I took pictures of the blue light response, which I rarely photograph since I currently don't have a blue-light blocking yellow filter - I taped yellow goggles in front of my camera lens. It works fine, but taping then removing the goggles without moving the camera was hard, discouraging me from doing it with many other specimens.

Shown respectively in the gallery below: Green laser (530 nm) fluorescence (note how the laser beam is split by the double refringence of the calcite), blue light (450 nm) fluorescence, longwave UV fluorescence, LW UV phosphorescence (very short lived), midwave UV (306 nm) fluorescence, shortwave UV fluorescence, SW UV phosphorescence, visible light. I didn't take pictures of the midwave UV phosphorescence, since it's similar to the SW UV afterglow.

405 nm violet/blue laser fluorescence is shown in a separate picture below the gallery; I show this picture separately, since none of the preset white balance settings of my camera could accurrately capture the color of the violet laser; I tried with a custom white balance setting, it didn't work either. Oddly, my old samsung cellphone camera had no problem capturing the color of the fluorescence (but the image quality is quite awful), so that's why I show this picture separately, since the specimen's position doesn't match with the other pictures as I had to photograph it separately.

***Important note: DO NOT experiment with lasers and minerals unless you really know what you are doing, and most importantly, NEVER do so without adequate protective goggles! Most minerals have highly reflective surfaces, as well as internal reflections, which inevitably result in the laser beam being reflected in various directions across the room; if the laser beam gets in unprotected eyes, a fraction of a second can be enough to lose eyesight! For green lasers, magenta or red goggles are required; for violet/blue lasers, yellow goggles are needed. Make sure that your goggles are actualy "antilasering" goggles, not just any colored goggles.

Size: 2,4 cm X 2,2 cm X 1,4 cm

405 nm violet/blue laser fluorescence.


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