Nenadkevichite
Nenadkevichite | |
---|---|
Nenadkevichite with ancylite crystals on the side | |
General | |
Category | Cyclosilicate |
Formula (repeating unit) | (Na,Ca)(Nb,Ti)Si2O7·2H2O |
Strunz classification | 9.CE.30a |
Crystal system | Orthorhombic |
Crystal class |
Dipyramidal (mmm) H-M symbol: (2/m 2/m 2/m) |
Space group | Pbam |
Identification | |
Color | Rose-pink, very light pink, light yellow, brown; dark brown due to inclusions |
Cleavage | Poor/ indistinct |
Fracture | Irregular/ uneven |
Tenacity | Brittle |
Mohs scale hardness | 5 |
Luster | Vitreous, dull |
Streak | White, very light rose-pink |
Diaphaneity | Transparent, translucent, opaque |
Specific gravity | 2.78 - 2.885 g/cm3 |
Nenadkevichite is a rare silicate mineral containing niobium with formula: (Na,Ca)(Nb,Ti)Si2O7·2H2O. It forms brown to yellow to rose colored orthorhombic dipyramidal crystals with a dull to earthy luster. It has a Mohs hardness of 5 and a specific gravity of 2.86.
It was first reported in 1955 from a nepheline syenite pegmatite in the Kola Peninsula. In addition it has been reported from Mont Saint-Hilaire, Canada; the Ilimaussaq complex, Greenland; Windhoek District, Namibia; and Zheltye Vody, Ukraine. It was named after Konstantin Avtonomovich Nenadkevich (1880–1963), Russian mineralogist and geochemist.
References
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