IMA 2021-113 = elliottite

database, nuove specie, discrediti,
ridefinizioni, classificazioni, ecc.
Rispondi
Avatar utente
Marco E. Ciriotti
Messaggi: 31675
Iscritto il: ven 25 giu, 2004 11:31
Località: via San Pietro, 55 I-10073 Devesi/Cirié TO - Italy
Contatta:

IMA 2021-113 = elliottite

Messaggio da Marco E. Ciriotti » gio 23 giu, 2022 16:31

Referenza:
▪ Grey I.E., Mumme W.G., MacRae C.M., Kampf A.R., Mills S.J. (2022): Elliottite, NaMgAl3(PO4)2F6·9H2O; a new crandallite-derivative mineral from Tom's phosphate quarry, Kapunda, South Australia.

Abstract:
Elliottite, NaMgAl3(PO4)2F6·9H2O, a new secondary phosphate mineral, is from Tom's phosphate quarry, Kapunda, South Australia. It occurs as hemispherical aggregates to 1 mm across comprising pseudohexagonal platelets overgrowing minyulite and amorphous angastonite on a matrix of goethite. Closely associated minerals are penriceite and wavellite. The calculated density is 2.09 g·cm-3. Optically the crystals are biaxial (+) with α = β = 1.475(2), γ = 1.479(2), 2V(calc) = 0°, orientation is Z ≈ c. There is no birefringence evident when viewing normal to the plates and the crystals display strong pseudo-uniaxial optical behaviour. Electron microprobe analyses give an empirical formula based on 23 anions of Na 0.56 K 0.40 Ca 0.02 Mg 1.79 Al 2.27 P 2.02 F 4.33 H 20.19 O 18.67. Elliottite is monoclinic, space group C2/m (#12), with a = 12.242(1) Å , b = 7.0118(7) Å, c = 11.2946(9) Å, β = 101.19(1)°, V = 951.1(2) Å 3 and Z = 2. The crystal structure was determined from an analysis of powder X-ray diff raction data. It represents a new type of crandallite-derivative layer structure, with the same topology of corner-connected aluminium-centred octahedra and PO4 tetrahedra as in crandallite, but with an expanded layer separation due to the location of Mg2(H2O)10 edge-shared octahedral dimers and water molecules in the interlayer region. Elliottite and penriceite have the same ideal formula and so are dimorphs: the structure of penriceite can be described as being derived from that of elliottite by periodic unit-cell-scale twinning.
Marco E. Ciriotti

«Things are interesting only in so far as they relate themselves to other things»

Avatar utente
Marco E. Ciriotti
Messaggi: 31675
Iscritto il: ven 25 giu, 2004 11:31
Località: via San Pietro, 55 I-10073 Devesi/Cirié TO - Italy
Contatta:

Re: IMA 2021-113 = elliottite

Messaggio da Marco E. Ciriotti » gio 30 giu, 2022 10:18

La referenza completa è la seguente:

▪ Grey I.E., Mumme W.G., MacRae C.M., Kampf A.R., Mills S.J. (2022): Elliottite, NaMgAl3(PO4)2F6·9H2O; a new crandallite-derivative mineral from Tom's phosphate quarry, Kapunda, South Australia. Australian Journal of Mineralogy, 23, 13-20.
Marco E. Ciriotti

«Things are interesting only in so far as they relate themselves to other things»

Rispondi

Chi c’è in linea

Visitano il forum: Nessuno e 48 ospiti