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.
IMA 2021-113 = elliottite
- 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
Marco E. Ciriotti
«Things are interesting only in so far as they relate themselves to other things»
«Things are interesting only in so far as they relate themselves to other things»
- 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
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.
▪ 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»
«Things are interesting only in so far as they relate themselves to other things»
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