Hackmanite and Richterite from Afghanistan

Contributed by: Michael Crawford
Date: Jul 5th, 2025
Locality: Unnamed Richterite occurrence, Ladjuar Medam, Sar-e-Sang, Kuran wa Munjan District, Badakhshan, Afghanistan (See on Mindat)
Size: 9 x 11.5 cm

Description:
This a four-color fluorescent specimen of hackmanite, richterite, fluorapatite, and calcite from Sar-e-Sang, Badakhshan Province, Afghanistan. The hackmanite in this specimen has very bright fluorescence under all UV wavelengths and the afterglow lasts for a very long time.

The bright fluorescence of the hackmanite allowed me to measure emission spectra. The other minerals are too dim to get sufficient signal for measurement. The longwave fluorescence is the typical orange color of sodalite/hackmanite caused by disulfide ions replacing chlorine. The longwave spectrum shows the vibronic signature characteristic of disulfide activation. The mid wave and shortwave fluorescence are a different color, blue-white. This fluorescence is activated by titanium (Ti3+) paired with an adjacent oxygen vacancy (Norrbo and others, 2017). This substitution occurs in the aluminum tetrahedra that make up the hackmanite cage. The titanium-oxygen vacancy is also the activator for the long lasting afterglow. Afterglow is strongest after exposure to midwave light. Afterglow also happens after shortwave UV exposure. The hackmanite also had dark purple tenebrescence after exposure to UV light.

The fluorescence of calcite and fluorapatite is brightest under midwave illumination. Calcite has a orange-red color and fluorapatite is violet. Richterite glows honey color under shortwave illumination.

Norrbo, I., Hyppänen, I., and Lastusaari, M. (2017) Up-conversion luminescence– A new property in tenebrescent and persistent luminescent hackmanites, J. of Luminescence, V.191, pp. 28-34.