Nifontovite Locality: Charcas , Municipio de Charcas, San Luis Potosí , Mexico ( Locality at mindat.org ) Size: thumbnail, 2.0 x .5 x .4 cm Nifontovite Unusually steep and bevelled termination on a stunning, perfect gem crystal with a perfect termination; and absolutely glassy, transparent surfaces. — Photo: Robert M. Lavinsky · CC BY-SA 3.0
Nifontovite
Nifontovite is an IMA-recognized mineral species in the oxides & hydroxide class, with the chemical formula Ca₃[BO(OH)₂]₆·2H₂O.
It crystallizes in the monoclinic crystal system (space group B2/b).
Key properties: Mohs hardness 3.5–5; specific gravity 2.35–2.36; Vitreous to silky luster; optically biaxial.
IMA symbol Nif, IMA status: approved, named in 1961.
Found in a skarn formed by quartz diorite intruding limestone (Novofrolovo mine, Russia); near gehlenite-spurrite skarn formed by hydrothermal alteration (Fuka, Japan).
It is found associated with Grossular-andradite, szaibélyite, sibirskite, calciborite, dolomite, calcite (Novofrolovo mine); olshanskyite, pentahydroborite, sibirskite, parasibirskite.
The mineral was named to honor Roman Vladimirovich Nifontov (1901-1960), Russian geologist who studied sedimentary and placer deposits.