White/colorless crystals of the extremely rare Sr carbonate-phosphate mineral crawfordite from type and only known locality worldwide in Russia (Koashva Mountain, Khibiny Massif, Murmansk Oblast, Russian Federation). Ex Vandenbroucke Museum collection specimen, from Waregem, Belgium. — Photo: David Hospital · CC BY-SA 4.0
Crawfordite
Crawfordite is an IMA-recognized mineral species in the phosphate class, with the chemical formula Na₃Sr(PO₄)(CO₃).
It crystallizes in the monoclinic crystal system (space group P2_1). It is a member of the Bradleyite structural group.
Key properties: Mohs hardness 3; specific gravity 3.05; Vitreous luster; optically biaxial.
IMA symbol Cfd, IMA status: approved, named in 1993.
A hydrothermal mineral in ultra-agpaitic pegmatites in a differentiated alkalic massif.
It is found associated with Pectolite, astrophyllite, barytolamprophyllite, shcherbakovite, vuonnemite, kazakovite, ershovite, chkalovite, natrite, villiaumite, rasvumite.
The mineral was named to honor Adair Crawford (1748–1795), Scottish physician and Professor of Chemistry, discoverer of strontium salts.