Newport New Hampshire, USA — Photo: Pacific Museum of Earth from Canada · CC BY-SA 2.0
Hurlbutite
Hurlbutite is an IMA-recognized mineral species in the phosphate class, with the chemical formula CaBe₂(PO₄)₂.
It crystallizes in the monoclinic crystal system (space group P2_1/a). It is a member of the Danburite structural group.
Key properties: Mohs hardness 6; specific gravity 2.877; White streak; Vitreous to greasy luster; optically biaxial.
IMA symbol Hrb, grandfathered status — known before the IMA’s founding, named in 1952.
A late-stage mineral in complex granite pegmatites; observed as an alteration product of beryl.
It is found associated with Triphylite, siderite, muscovite, albite, quartz (G.E. Smith mine, New Hampshire, USA); montebrasite, beryllonite, lithiophilite (Viitaniemi pegmatite.
The mineral was named to honor Prof. Cornelius Searle Hurlbut, Jr. (1906–), American mineralogist, Harvard University, Cambridge, Massachusetts, USA.