Hydroxylherderite from Pakistan
Contributed by: Michael Crawford
Date: Jun 30th, 2025
Locality: Shigar District, Gilgit-Baltistan, Pakistan (See on Mindat)
Size: 2.5 x 2 x 3 cm
Description:
This is a small crystal of hydroxylherderite (CaBe(PO4)(OH)) from Shigar District, Pakistan. It fluoresces a bright blue under all wavelengths of UV illumination. The fluorescence is reminiscent of fluorite fluorescence, but the emission spectra clearly show this hydroxylherderite fluorescence differs from fluorite fluorescence. The hydroxylherderite emission peaks at 442 nm whereas the fluorite peak is 421 nm. This hydroxylherderite is also fluorescent in the ultraviolet region with peaks at 338 nm and 365 nm. The specific activators for hydroxylherderite are not well-documented, but rare earth elements (REE) are likely candidates.
Summary of luminescence responses:
Hydroxylherderite (Mindat) (RRUFF)
- Fluorescence under Longwave (365nm LED) UV light: Blue
- Fluorescence under Midwave (305nm LED) UV light: Blue
- Fluorescence under Shortwave (255nm LED) UV light: Blue