Posted On: Friday, March 6, 2015
The geology community knows a lot about mineral fluorescence under excitation by various wavelengths of ultraviolet light but when it comes to excitation by light in the visible portion of the spectrum, such as blue, … not so much. In December 2013 Charles Mazel (NIGHTSEA) and Earl Verbeek (Sterling Hill Mining Museum) explored the extensive collection of the Franklin Mineral Museum (Franklin, New Jersey, USA) for instances of blue-light-stimulated fluorescence. When fluorescence occurred the specimen was photographed under white light, fluorescing under blue light, and fluorescing under either or both of shortwave and longwave ultraviolet light. The results were published in September 2014 – Mazel, C.H. and Verbeek, E.R. (2014), Fluorescence of minerals under blue light. The Picking Table (Journal of the Franklin-Ogdensburg Mineralogical Society), vol. 55, no. 2, p. 13-25.
We will share the photographic results in a series of blog posts, each documenting one specimen. See the summary of all posts to date.
The editors of The Picking Table have graciously allowed us to make the fall 2014 issue with our article on blue light mineral fluorescence available for free download. Click the image of the cover to access the pdf. And we certainly encourage you to join FOMS so that you can keep up with their activities and receive future issues.
Johannsenite was not previously documented to be a fluorescent mineral. Its yellow emission under blue light is a new discovery.
Mineral (primary) – Johannsenite
Specimen identifier – FMM 1864
Approximate size (cm) – 10.5 x 8 x 7
White light – Tan fuzzy crystals are johannsenite; orange is axinite-(Mn); white grains are calcite in part; dark rock along base and at left is franklinite-rich zinc ore
Blue light – fluorescence: zoned yellow crystals are johannsenite; red is calcite; green is willemite
Shortwave ultraviolet – fluorescence: barely perceptible brown is johannsenite; red is calcite; green is willemite
Longwave ultraviolet – fluorescence: dim orange to brown is johannsenite; dim red is calcite; green is willemite; blue dots and threads are lint
(Click on image for larger view)