Haleniusite-(La) from the Bastnas Deposit, Vastmanland, Sweden; a new REE oxyfluoride mineral species

Haleniusite-(La) was found on the dumps of the Bastnäs Cu-REE mines associated with bastnäsite-(La), brochantite, ferriallanite-(Ce) and quartz. It is powdery with a distinct yellow colour; it has ncalc ∼1.9, Dcalc. 6.5 g/cm3. Chemical analysis gave La 36.3, Ce 36.6, Pr 1.5, Nd 6.3, Sm 0.0, O 9.6, F...

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Bibliographic Details
Published in:	Canadian mineralogist Vol. 42; no. 4; pp. 1097 - 1103
Main Authors:	Holstam, Dan, Grins, Jekabs, Nysten, Per
Format:	Journal Article
Language:	English
Published:	Mineralogical Association of Canada 01-08-2004
Subjects:	Bastnas Deposit chemical composition concentration crystal structure crystal systems cubic system fluorides formula geochemistry haleniusite halides lattice parameters metals Mineralogy new minerals nonsilicates oxyfluorides rare earths Rietveld refinement unit cell Vastmanland Sweden X-ray diffraction data
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Description
Summary:	Haleniusite-(La) was found on the dumps of the Bastnäs Cu-REE mines associated with bastnäsite-(La), brochantite, ferriallanite-(Ce) and quartz. It is powdery with a distinct yellow colour; it has ncalc ∼1.9, Dcalc. 6.5 g/cm3. Chemical analysis gave La 36.3, Ce 36.6, Pr 1.5, Nd 6.3, Sm 0.0, O 9.6, F 10.0, = 100.3, leading to the idealized formula (La,Ce)OF. Indexed XRD powder data are tabulated; strongest lines 3.25(100), 1.991(61), 1.697(46), 2.815(31), 1.292(15) Å; a 5.6282 Å, V 178.28 Å3, Z = 4, space group Fm3m. It is cubic, isostructural with fluorite. Haleniusite is a secondary mineral formed by alteration of primary bastnäsite-(La), probably via a decarbonation reaction (La,Ce)CO3F → (La,Ce)OF + CO2. The name is to honour Ulf Halenius, Professor of Mineralogy at the Swedish Museum of Natural History.
ISSN:	0008-4476 1499-1261
DOI:	10.2113/gscanmin.42.4.1097