is a mineral belonging to the apatite
group, with formula CaBe(PO4
)(F,OH). It forms monoclinic
crystals, often twinned
and variable in colour from colourless through yellow, green or purple.
It is found in many parts of the world, often in pegmatites and associated with other apatite minerals.
It is named after Sigmund August Wolfgang von Herder, a mining official from Saxony.