Referenza:
▪ Kampf, A.R., Smith, J.B., Hughes, J.M., Ma, C., Emproto, C. (2023): New Minerals from the Redmond Mine, North Carolina, USA: I. Redmondite, Hydroredmondite, and Sulfatoredmondite, Three Minerals Containing the Novel [Pb8O2Zn(OH)6]8+ Structural Unit. The Canadian Journal of Mineralogy and Petrology, 61, 189-202.
Abstract:
The new minerals redmondite (IMA2021–072), [Pb8O2Zn(OH)6](S2O3)4, hydroredmondite (IMA2021–073), [Pb8O2Zn(OH)6](S2O3)4·2H2O, and sulfatoredmondite (IMA2021–089), [Pb8O2Zn(OH)6](SO4)4·6H2O, were found in the Redmond mine, Haywood County, North Carolina, USA, where they occur together in a highly unusual secondary assemblage that comprises a variety of rare Pb-Zn-Cu sulfates, thiosulfates, and carbonates. The properties of redmondite are as follows: colorless to shades of brown, transparent equant rhombs to about 1 mm; white streak; adamantine luster; brittle; Mohs hardness 2; conchoidal fracture; no cleavage; 5.757 g/cm3 calculated density; biaxial with α = 1.96–1.97, β = 1.97–1.98, γ = 1.97–1.98; extreme dispersion. The properties of hydroredmondite are as follows: colorless, transparent prisms, blades, and tablets up to about 1 mm; white streak; adamantine luster; brittle; Mohs hardness 2; curved and stepped fracture; good cleavages on {101} and {10-1}; 5.124 g/cm3 calculated density; biaxial (+) with α = 1.830(5), β = 1.880(calc), γ = 1.950(calc), 2Vmeas = 83(1)°. The properties of sulfatoredmondite are as follows: colorless, transparent wedge-shaped crystals to about 2 mm; white streak; adamantine luster; brittle; Mohs hardness 2; curved, irregular fracture; no cleavage; 5.173 g/cm3 calculated density; biaxial (+), α = 1.780(5), β = 1.850(calc), γ = 1.860(calc), 2Vmeas = 40(3)°; moderate r > v dispersion. Electron probe microanalyses provided the empirical formulae: Pb8.16Zn1.00S6+3.97S2−3.97O20H5.79, Pb8.00Zn1.00S6+4.00S2−4.00O22H9.98, and Pb8.00Zn0.99S6+4.00S2−0.89O29.11H17.98 for redmondite, hydroredmondite, and sulfatoredmondite, respectively. Redmondite is monoclinic, P21/c, a = 9.1672(4), b = 10.6576(4), c = 14.0620(10) Å, β = 101.173(7)°, V = 1347.83(12) Å3, and Z = 2. Hydroredmondite is monoclinic, P21/n, a = 12.5991(9), b = 9.2819(4), c = 12.9774(9) Å, β = 90.443(6)°, V = 1517.57(16) Å3, and Z = 2. Sulfatoredmondite is monoclinic, C2/m, a = 17.294(2), b = 7.3668(9), c = 12.7271(18) Å, β = 110.622(9)°, V = 1517.5(4) Å3, and Z = 2. The crystal structures of redmondite (R1 = 0.0346 for 2061 I > 2σI), hydroredmondite (R1 = 0.0346 for 3022 I > 2σI), and sulfatoredmondite (R1 = 0.0344 for 1661 I > 2σI) are all based on the same [Pb8O2Zn(OH)6]8+ structural unit.
IMA 2021-072, IMA 2021-073, IMA 2021-089 = redmondite, hydroredmondite, sulfateredmondite
- Marco E. Ciriotti
- Messaggi: 31675
- Iscritto il: ven 25 giu, 2004 11:31
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IMA 2021-072, IMA 2021-073, IMA 2021-089 = redmondite, hydroredmondite, sulfateredmondite
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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