Håleniusit- (La)

Håleniusit- (La)
	Yellow håleniusite (La) and green brochantite on gray cerite (Ce) from the Bastnäs pit near Riddarhyttan ( Skinnskatteberg , Sweden) ; ( overall size of the step: 5.0 cm × 3.0 cm × 1.5 cm)
General and classification
other names	IMA 2003-028
chemical formula	LaOF
Mineral class; (and possibly department)	Halides
System no. to Strunz ; and to Dana	3.DE.05 ( 8th edition : III / A.08) ; 02/10/10/01
Crystallographic Data
Crystal system	cubic
Crystal class ; symbol	cubic hexakisoctahedral; 4 / m 3 2 / m
Space group	Fm 3 m (No. 225)
Lattice parameters	a = 5.6282 Å
Formula units	Z = 4
Physical Properties
Mohs hardness	not defined
Density (g / cm 3 )	calculated: ≈ 6.5
Cleavage	not defined
colour	lemon to ocher yellow
Line color	light yellow
transparency	not defined
shine	matt, earthy
Crystal optics
Refractive index	n = 1.9 (calculated)

Håleniusit- (La) is a mineral from the mineral class of halides with the idealized chemical composition LaOF and is therefore chemically a lanthanum- oxy fluoride . As in the samples analyzed by Håleniusit- (La) as a foreign admixtures other earth metals of the rare were found (mainly cerium with a proportion of up to 35%), the chemical formula in a variety of sources with (La, Ce) OF is indicated .

Håleniusit- (La) crystallizes in the cubic crystal system , but develops only microscopic crystals of yellow color, which mainly form in the form of crusty or powdery coatings and cavity fillings on and in other minerals (mostly bastnasite ).

Etymology and history

The mineral was first described by Dan Holtstam, Jekabs Grins and Per Nysten in 2004 and named after the Swedish mineralogist Ulf Hålenius (* 1951), who worked at Naturhistoriska riksmuseet . The holotype on which this description is based was found in 1986 by Jörgen Langhof in the Bastnäs mines near Riddarhyttan, Sweden, and is in the Naturhistoriska riksmuseet (catalog no. 20030025). It consists mainly of ferric alanite (Ce) . The Håleniusit- (La) replaced a large part of the Bastnäsit- (La) which was also contained in the course of storage and formed a yellow layer a few millimeters thick.

Records from Uppsala University from the early 19th century already mention "earthy" or lemon-yellow bastnäsite, which Holtstam later confirmed to contain håleniusite (La).

classification

In the outdated, but still in use, 8th edition of the mineral classification according to Strunz , Håleniusit- (La) belonged to the division of "simple halides", where together with coccinite , fluorite , frankdicksonite , gagarinite- (Y) , gagarinite- (Ce) ( formerly Zajacit- (Ce) ), Laurelit and Tveitit- (Y) the "Fluorite series" with the system no. III / A.08 .

The 9th edition of Strunz's mineral systematics, which has been in effect since 2001 and is used by the International Mineralogical Association (IMA), classifies Håleniusit- (La) in the division of "oxyhalides, hydroxyhalides and related double halides". This is further subdivided according to the predominant metals in the compound, so that the mineral can be found according to its composition in the subdivision "with rare earth elements (REE)", where it is the only member of the unnamed group 3.DE.05 .

The systematics of minerals according to Dana , which is mainly used in the English-speaking world , assigns Håleniusit- (La) to the class of "halides" and there in the department of "oxyhalides and hydroxyhalides". Here he is the only member of the unnamed group 10.02.10 within the sub-section "Oxihalides and hydroxyhalides with the formula A (O, OH) X _q ".

Crystal structure

Håleniusit- (La) crystallizes in the cubic crystal system in the space group Fm 3 m (space group no. 225) , the lattice parameter a = 5.6282 Å and four formula units per unit cell . Template: room group / 225

Education and Locations

Håleniusite- (La) is a secondary mineral that is formed during the conversion of Bastnasite- (La) , most likely through a decarbonization reaction:

(La, Ce) CO ₃ F → (La, Ce) OF + CO ₂ .

Håleniusit- (La) is quite widespread in the Bastnäs pits near Riddarhyttan (also type locality ), a place in the Swedish municipality of Skinnskatteberg . It occurs, among other things, in paragenesis with bastnesite (La), ferricallanite (Ce) , brochantite and quartz .

literature

Dan Holtstam, Jekabs Grins, Per Nysten: Håleniusite- (La) from the Bastnäs deposit, Västmanland, Sweden: A new REE oxyfluoride mineral species. In: Canadian Mineralogist , Volume 42 (Issue 4), 2004, pp. 1097–1103 ( PDF 709.2 kB ).

Web links

Commons : Håleniusite- (La) - collection of images, videos and audio files

Individual evidence

↑ ^a ^b IMA / CNMNC List of Mineral Names; March 2016 (PDF 1.55 MB; p. 74)
↑ ^a ^b Webmineral Håleniusite- (La) (English)
↑ ^a ^b ^c ^d ^e ^f Holtstam, Grins, Nysten: Håleniusite- (La) from the Bastnäs deposit, Västmanland, Sweden: A new REE oxyfluoride mineral species. P. 1097.
↑ Holtstam, Grins, Nysten: Håleniusite- (La) from the Bastnäs deposit, Västmanland, Sweden: A new REE oxyfluoride mineral species. P. 1098.

[IMA-Liste-2016-03-1] IMA / CNMNC List of Mineral Names; March 2016 (PDF 1.55 MB; p. 74)

[Webmineral-2] Webmineral Håleniusite- (La) (English)

[Holstam-3] ↑ ^a ^b ^c ^d ^e ^f Holtstam, Grins, Nysten: Håleniusite- (La) from the Bastnäs deposit, Västmanland, Sweden: A new REE oxyfluoride mineral species. P. 1097.

[Holstam2-4] Holtstam, Grins, Nysten: Håleniusite- (La) from the Bastnäs deposit, Västmanland, Sweden: A new REE oxyfluoride mineral species. P. 1098.