Aragonite and Calcite with Sulfur - Italy

Contributed by: Mark Cole
Date: Apr 6th, 2026
Locality: La Grasta Mine (Grasta Mine), Caltanissetta, Caltanissetta Province, Sicily, Italy (See on Mindat)
Size: 3 x 2 x 5.5 inches
Weight: 20.3 oz

Description:
Pieces from Italy are simply the best example of aragonites around IMHO. This piece has large aragonite crystals on a bed of needle calcite crystals. They both respond differently under SW, LW, and MW and are both very phosphorescent. The sulfur, although it looks like it might show a dull fluorescence, is not fluorescent. It is just reflecting the fluorescent colors of the aragonite.

There are two sets of images, one for each side. The first set shows the color shift under SW, MW, and LW. The second set shows the other side very dramatically under all three wavelengths at once, as well as the phosphorescence and SW only.

The closeup image shows the delicate calcite crystals under the aragonite.

Originally posted by Mark Cole on Nature's Rainbows in 2016.