Afghanite Crystal
Contributed by: Michael Crawford
Date: Jul 5th, 2025
Locality: Ladjuar Medam, Sar-e-Sang, Kuran wa Munjan District, Badakhshan, Afghanistan (See on Mindat)
Size: 5.5 x 7.5
Description:
A hexagonal afghanite ((Na,K)22Ca10(Si24Al24O96)(SO4)6Cl6) crystal jutting out from calcite matrix from Sar-e-Sang, Badakhshan Province, Afghanistan. The crystal is 6 cm long. This crystal has yellow-orange fluorescence under longwave light. It is non-fluorescent in midwave and shortwave UV light. The emission spectrum of the crystal has a broad peak with several smaller peaks superimposed on it. This vibronic signature is characteristic of the disulfide activator. The disulfide ion substitutes for either the sulfate (SO4) or the chlorine (Cl-) ion.
The calcite matrix fluoresces red under midwave light, and it is dimmer under shortwave light. The midwave emission spectrum peaks at 619 nm. Manganese replacing calcium activates this red fluorescence. The shortwave emission has very bright ultraviolet fluorescence that is significantly brighter than the visible red fluorescence. The emission spectrum has two sharp peaks at 339 nm and 362 nm. This ultraviolet fluorescence is activated by cerium.
Summary of luminescence responses:
Afghanite (Mindat) (RRUFF)
- Fluorescence under Longwave (365nm LED) UV light: Yellow
- Fluorescence under Midwave (305nm LED) UV light: Red