Referenza:
▪ Grey, E., Kampf, A.R., Keck, E., Cashion, J.D., MacRae, C.M., Gozukara, Y., Shanks, F.L. (2019): Ferrirockbridgeite, (Fe0.673+□0.33)2(Fe3+)3(PO4)3(OH)4(H2O), and the oxidation mechanism for rockbridgeite-group minerals. European Journal of Mineralogy, 31, (in press).
Abstract:
Ferrirockbridgeite, ideally (Fe3+0.67Fe0.673+□0.33)2(Fe3+)3(PO4)3(OH)4(H2O), is a new member of the rockbridgeite group. The type specimen is from the Palermo No. 1 pegmatite in North Groton, Grafton County, New Hampshire, USA. Electron microprobe analysis, coupled with Mössbauer spectroscopy for FeO and thermogravimetric analysis (TGA) for H2O gives the empirical formula Mn0.312+Fe0.082+Mg0.01Zn0.03Ca0.05Fe4.183+P2.87O17H6.11. Ferrirockbridgeite is orthorhombic, space group Bbmm with a = 13.853(1), b = 16.928(1), c = 5.1917(5) Å and Z = 4. Optically, ferrirockbridgeite is biaxial (–), with α = 1.875(5), β = 1.890(calc), γ = 1.900(5) (measured in white light) and 2V (meas) is 78(1)° from extinction data. The dispersion is strong, with r > v. The optical orientation is X = c, Y = a, Z = b. The pleochroism is X = yellow brown, Y = olive brown, Z = dark olive green; Z > Y > X. Crystal structure refinements on ferrirockbridgeite and other oxidized rockbridgeite-group species, including type rockbridgeite and type frondelite, show that oxidation is accompanied by loss of Fe2+ from the M2 site according to the reaction [3Fe2+] → [2Fe3+ + □] + Fe2+(removed) +2e−. A variable portion of the Fe removed from the M2 site becomes trapped at M3 site vacancies. A general formula for oxidized rockbridgeite-group minerals is presented.
IMA 2018-065 = ferrirockbridgeite
- Marco E. Ciriotti
- Messaggi: 31645
- Iscritto il: ven 25 giu, 2004 11:31
- Località: via San Pietro, 55 I-10073 Devesi/Cirié TO - Italy
- Contatta:
IMA 2018-065 = ferrirockbridgeite
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: 31645
- Iscritto il: ven 25 giu, 2004 11:31
- Località: via San Pietro, 55 I-10073 Devesi/Cirié TO - Italy
- Contatta:
Re: IMA 2018-065 = ferrirockbridgeite
Pubblicata.
Referenza:
▪ Grey, E., Kampf, A.R., Keck, E., Cashion, J.D., MacRae, C.M., Gozukara, Y., Shanks, F.L. (2019): Ferrirockbridgeite, (Fe0.673+□0.33)2(Fe3+)3(PO4)3(OH)4(H2O), and the oxidation mechanism for rockbridgeite-group minerals. European Journal of Mineralogy, 31, 585-594.
Referenza:
▪ Grey, E., Kampf, A.R., Keck, E., Cashion, J.D., MacRae, C.M., Gozukara, Y., Shanks, F.L. (2019): Ferrirockbridgeite, (Fe0.673+□0.33)2(Fe3+)3(PO4)3(OH)4(H2O), and the oxidation mechanism for rockbridgeite-group minerals. European Journal of Mineralogy, 31, 585-594.
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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