Herderite Locality: Shigar Valley, Skardu District, Baltistan, Northern Areas, Pakistan (Locality at mindat.org) Size: miniature, 3.8 x 3.5 x 2.5 cm Herderite G — Photo: Robert M. Lavinsky · CC BY-SA 3.0
Herderite
A calcium-beryllium phosphate of granitic pegmatites, colorless to green and often twinned.
Intro adapted from Wikipedia (CC BY-SA).
Herderite is an IMA-recognized mineral species in the phosphate class, with the chemical formula CaBe(PO₄)F.
It crystallizes in the monoclinic crystal system (space group P2_1/a). It is a member of the Gadolinite structural group.
Key properties: Mohs hardness 5–5.5; specific gravity 3.02; typically colorless or white or yellow or green or brown; white streak; Vitreous luster; refractive index 1.591; optically biaxial.
IMA symbol Hrd, grandfathered status — known before the IMA’s founding, named in 1828.
Probably from a complex granite pegmatite.
The mineral was named to honor Siegmund August Wolfgang von Herder (1776–1838), mining official, Freiberg, Saxony, Germany.
Collections: Collector Favorites, Rare & Remarkable.