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 - it is just reflecting the fluorescent colors of the aragonite.
Two galleries are shown, one for each side. The first gallery after the closeup shows the color shift under SW, MW, and LW. The 2nd shows the other side very dramatically under all three wavelengths at once, as well as the phosphorescence and SW only.
The first pic is a closeup showing the delicate calcite crystals under the aragonite.