Hydroxynatropyrochlore
Hydroxynatropyrochlore is an IMA-recognized mineral species in the oxides & hydroxide class, with the chemical formula (Na,Ca,Ce)₂Nb₂O₆(OH).
It crystallizes in the cubic crystal system (space group Fd-3m). It is a member of the Pyrochlore-Pyrochlore structural group.
Key properties: Mohs hardness 5; specific gravity 4.6; White streak; Adamantine to greasy luster.
IMA symbol Hnpcl, IMA status: approved, named in 2017.
A secondary hydrothermal mineral resulting from the alteration of Nb-rich baddeleyite in low-carbonate phoscorite in the contact zone of a phoscorite-carbonatite pipe with host foidolite as well as in the carbonate-rich phoscorite and carbo.
It is found associated with Calcite, dolomite, forsterite, hydroxylapatite, magnetite, phlogopite, baddeleyite, barite, barytocalcite, chalcopyrite, chamosite-clinochlore, galena.
The name refers to a member of the pyrochlore group with prefixes to indicate dominant OH- (hydroxy) in the Y site and dominant sodium (natro) in the A site.