Hydroxyferroroméite, a new secondary weathering mineral from Oms, France

Hydroxyferroroméite, ideally (Fe2+ 1.5[]0.5)Sb5+ 2O6(OH), is a new secondary mineral from the Correc d'en Llinassos, Oms, Pyrénées-Orientales Department, France. Hydroxyferroroméite occurs as yellow to yellow-brown powdery boxwork replacements up to about 50μm across after tetrahedrite in a siderite–quartz matrix. No distinct crystals have been observed. The empirical formula (based on 7 (O + OH) per formula unit, pfu) is (Fe2+ 1.07Cu2+ 0.50Zn0.03Sr0.03Ca 0.01[]0.36)Σ2 (Sb5+ 1.88Si0.09Al0.02As0.01)Σ2 O6 ((OH)0.86 O0.14). X-ray photoelectron spectroscopy was used to determine the valence states of Sb, Fe and Cu. Hydroxyferroroméite crystallises in the space group Fd3 m with the pyrochlore structure and hence is a new Fe2+ -dominant member of the roméite group of the pyrochlore supergroup. It has the unit-cell parameters: a = 10.25(3) Å, V = 1077(6) Å3 and Z = 8. A model, based on bond-valence theory, for incorporation of the small Fe2+ cation into a displaced variant of the A site of the pyrochlore structure is proposed.

Citation

Mills, Stuart J.; Christy, Andrew G.; Rumsey, Mike S.; Spratt, John; Bittarello, Erica; Favreau, Georges; Ciriotti, Marco E.; Berbain, Christian (2017_ Hydroxyferroroméite, a new secondary weathering mineral from Oms, France. European Journal of Mineralogy Vol. 29 No. 2, p. 307 - 314

Type

Journal Article

Item Description

The attached document is the author(’s’) final accepted/submitted version of the journal article. You are advised to consult the publisher’s version if you wish to cite from it.
NHM Repository

ISSN

0935-1221

EISSN

1617-4011