Workgroup    Fluorescence

Fluorite octahedral cleavages, Cave-in-Rock, Cave-in-Rock Sub-District, Illinois - Kentucky Fluorspar District, Hardin Co., Illinois, USA  (
Activator blue fluorescence: Eu2+ partially replacing Ca2+
Activator golden yellow fluorescence: inclusions of droplets of brine from which the fluorite grew. Possibly with some contribution of organic matter.

Fluorite: Hammam-Zriba Mine, Zriba-Village, Zaghouan Governorate, Tunisia (
Activator light blue fluorescence: organic material.

Fluorite:Seilles, Andenne, Namur Province, Belgium (
Activator blue fluorescence: Eu2+ replacing Ca2+
Activator red fluorescence: M-center (2F+Na+)
Specimens from collection of the KBIN in Brussels
fluorite seilles 2
fluorite seilles 3

Fluorite: Frazer's Hush Mine, Rookhope District, Weardale, North Pennines, Co. Durham, England, UK (
Activator blue fluorescence fluorite: Eu2+ replacing Ca2+
Activator red fluorescence calcite: not yet investigated, probably Mn2+ and Pb2+

Halite: Fulda, Hessen, Germany
Activator red fluorescence: Mn2+ replacing Na+ with Pb2+ as a co-activator.

Halite: Wintershall Potash Works, Heringen, Werra valley, Hessen, Germany (
Activator red fluorescence: Mn2+ replacing Na+ with Pb2+ as a co-activator.

Halite: Rudna Mine, Lubin District, Legnica, Lower Silesia, Poland (
Activator red fluorescence: Mn2+ replacing Na+ with Pb2+ as a co-activator.
long wave UV
Long wave UV + midrange UV
Short wave UV

Villiaumiet: Aris Quarries, Aris, Windhoek District, Khomas Region, Namibia (
Activator orange fluorescence: Intrinsic: M-centers (M-center = 2 F-centers + M+    (Na+, H+ etc.))
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long wave UV
long wave UV
Short wave UV
Short wave UV
Short wave UV
Yttrofluorite in normal light
Yttrofluorite long wave UV
Yttrofluorite in short wave UV

Fluorite var.: Yttrofluorite: (
The fluorescence is caused by rare earth elements that partially replace calcium. Yttrium itself does not partake in this fluorescence, but it is the 'main contaminant'. Check out the spectrum for more information about this fluorescence.
          White light                             long wave UV                       short wave UV
Fluorite octahedral cleavages
Fluorite var. Yttrofluorite
White light and Midrange UV resp.

Navidad Mine?, Abasolo, Rodeo, Mun. de Rodeo, Durango, Mexico

Creedite is not generally known for its fluorescence. It doensn't fluoresce consistently and when it does, it's not always for the same reason. Specimens from La Paz, Bolivia, in my collection fluoresce a lot like calcite and gypsum: light blue-green. This is usually caused by some organic matter, mostly humic acids. This creedite specimen from Durango fluoresces a clear violet-blue, clearly different from the blue-green fluorescence of the Bolivian specimen. Both specimens have a distinct greenish phosphorescence, which is a clear indication that they both contain polycyclic aromatic hydrocarbons (humic acids). It appears that the Mexican specimen also contains some gadolinium, cerium and europium that account for a violet-blue fluorescence. In this specimen, the ratio between the violet-blue and the bleu-green fluorescence sways towards the violet blue, but both are present. Go see the spectrum for more details.
Het heuvelachtige land van Qinglong Co. (Photo Sunny Luo)
Talrijke grotten en holten in de bodem... (Photo Sunny Luo)
Weelderige begroeiing levert humuszuren op (Photo Sunny Luo)
Bruine verkleuring wijst op ingesloten organisch materiaal
Organisch materiaal fluoresceert sterk!
Creediet vormt perfecte kristallen die in groepjes groeien
Vaak resulterend in bolvormige aggregaatjes
met een sterke fluorescentie, blauw tot blauwgroen. Typisch voor organisch materiaal
Creedietspecimen in wit licht.
Zelfde specimen onder 365 nm LW UV. Fluorescenite in drie kleuren.
De letters A,B en C markeren de plaatsen waar het spectrum werd gemeten.
Spectrum van de witte fluorescentie
Spectrum van de blauwe fluorescentie
Spectrum van de roze fluorescentie
Creedite can apparently fluoresce due to more than one activator. However, specimens from China manage to pleasantly surprise us. They are found in the hilly area of Qinglong County, where locals look for them in the abundant caves and hollows. The lush vegetation and porous soil make it easy to incorporate humic acids and other organic plant residues into the creedite crystals (see photos).
Some crystal groups are therefore colored brown and fluoresce strongly blue-green under UV. I received a number of specimens from my e-friend Hercule Shen, which show very different fluorescence colors. One of them shows no less than three different colors in long wave UV, 365 nm.
1) White : The spectrum shows peaks of organic fluorescence/phosphorescence around 450 nm. A strong peak around 490 nm could indicate the presence of titanium as [TiO6]8-. No analyses have been carried out to confirm this, but ilmenite(Fe2+TiO3) is found in the site, which makes the presence of titanium in creedite plausible.
2) Blue : an emission peak around 410 nm seems to point to the presence of trivalent cerium. The peak has been somewhat widened by the underlying emissions of the organic matter. Here too we see a peak of [TiO6]8- but this peak has also widened and shifted a bit, probably due to the presence of divalent europium that likes to fluoresce in that wavelength range.
3) Pink : around 570 nm we see a fairly sharp peak that is most likely caused by divalent manganese that replaces some calcium. Here, too, the emission of titanium is prominent. This reduces the saturation of the red Mn2+emission to a pale pink.
So you see, creedite is a real chameleon when it comes to fluorescence.
Qinglong County, Qianxinan, Guizhou, China
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