Hurlbutite: Gemstone Information
Hurlbutite is CaBe2(PO4)2 and forms stout monoclinic transparent to translucent colourless to greenish white crystals with hardness 6 and SG 2.90. The RI for the alpha, beta and gamma rays is 1.595, 1.601 and 1.604,biaxial negative with birefringence 0.009. Hurlbutite occurs as a latestage mineral in complex granite pegmatites. Some material has been fashioned from the G.E. Smith mine, Newport, Sullivan County, New Hampshire, USA.