It has been reported that crystals of sulfur from Maybee, Michigan, occasionally show weak yellow fluorescence under UV (Robbins, Fluorescence- Gem and Minerals Under Ultraviolet Light, 1994, p. 192). This is a specimen of yellow sulfur crystals on a bed of calcite and celestine druse, from the Maybee Quarry, Maybee, Monroe Co., Michigan. This piece shows bright fluorescence and phosphorescence under UV, but is the sulfur fluorescent? Looking at the photos taken under UV, the sulfur appears to be fluorescing a dim yellow/green color, especially under long wave. However, the sulfur is quite translucent. Could it be that the sulfur is simply transmitting the light emitted by the calcite and celestine? As an experiment, I took a small piece of sulfur from this specimen, and checked it for fluorescence (in the absence of matrix) under all UV wavelengths. Alas, it is not fluorescent. Therefore, the apparent fluorescence of the sulfur on this specimen is simply the result of the transmission of the fluorescent light emitted by the calcite and celestine. My search for the elusive fluorescent sulfur from Maybee continues...
Fluorescence under long wave UV (365 nm). The apparent yellow-green fluorescence of the sulfur is an illusion caused by the transmission of the fluorescent light emitted by the calcite and celestine.
Green phosphorescence is seen following exposure to long wave UV.
Fluorescence under short wave UV (254 nm). Again, the apparent fluorescence of the sulfur is an illusion and is not real.
Blue-green phosphorescence is seen following exposure to short wave UV.
The same specimen shown under visible light. The size of this piece is 10.8 x 8.0 x 3.6 cm, and it weighs 269 grams.