Pargasite and Calcite from Afghanistan
Contributed by: Michael Crawford
Date: Jun 20th, 2025
Locality: Sar-e-Sang River, Sar-e-Sang, Kuran wa Munjan District, Badakhshan, Afghanistan (See on Mindat)
Size: 12 x 16 cm
Description:
The pargasite (NaCa2(Mg4Al)(Si6Al2)O22(OH)2) in this specimen was confirmed through XRD analysis. The honey brown color distinguishes it from other pargasite specimens from localities such as Vietnam and New Jersey, which are green. This pargasite and calcite specimen originates from Sar-e-Sang, Badakhshan Province, Afghanistan. Afghan pargasite resembles richterite/winchite found at Sar-e-Sang. Richterite/winchite crystals often exhibit striations parallel to the long axis of the crystal, which are absent in pargasite. Both minerals fluoresce yellowish white under shortwave UV light. However, in strong longwave UV illumination, the pargasite fluoresces a dim dark red color.
The yellowish white fluorescence of pargasite under shortwave UV differs from the greenish fluorescence observed in pargasite from Vietnam and New Jersey. Shortwave emission spectra of the pargasite show a broad peak with a maximum at 483 nm and a smaller peak at 588 nm. There are no references indicating which elements activate the pargasite fluorescence. The dark red fluorescence under longwave UV suggests manganese as a possible activator. Titanium is another potential activator.
Calcite fluorescence is the most intense under midwave illumination. The midwave spectrum exhibits a broad peak with a maximum at 618 nm, indicating a manganese activator. The shortwave spectrum shows very bright ultraviolet fluorescence, likely activated by cerium. The presence of other rare earth element (REE) activators is indicated in the emission spectrum created by 405 nm laser illumination, with peaks at 564 nm, 600 nm, and 647 nm.
Summary of luminescence responses:
Pargasite
- Fluorescence under Longwave (365nm LED) UV light: Red
- Fluorescence under Shortwave (255nm LED) UV light: Yellow
- Fluorescence under Midwave (305nm LED) UV light: Red
- Fluorescence under Shortwave (255nm LED) UV light: Red