IMA 2018-005 = belogubite

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Marco E. Ciriotti
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IMA 2018-005 = belogubite

Messaggio da Marco E. Ciriotti » mer 07 ago, 2019 12:11

Referenza:
▪ Kasatkin, A.V., Britvin, S.N., Chukanov, N.V., Škoda, R., Agakhanov, A.A., Belakovskiy, D.I. (2019): Belogubite, a new mineral of the chalcanthite group from the Gayskoe deposit, South Urals, Russia. Zapiski RMO, 148(3), 30-43.

Abstract:
Belogubite, ideally CuZn(SO4)2·10H2O, has been found in the supergene zone uncovered by the open pit at the Gayskoe massive sulfide Zn-Cu deposit (Orenburgskaya region, the South Urals, Russia). It is associated with dietrichite and may contain relics of quartz. Belogubite forms aggregates of blue grains up to 1 mm in size. The mineral is transparent with vitreous luster and white streak. Its color varies from pale equant to light blue. Cleavage and parting were not observed. The new mineral is brittle and has Mohsʼ hardness ca. 2½. Its density measured by floatation in bromoform+ethanol is 2.27(2) g/cm–3, its calculated density is 2.249 g/cm–3. Belogubite is biaxial (–), α = 1.512(2), β = 1.525(2), γ = 1.531(2); 2V (meas.) = 70(10)°, 2V (calc.) = 67.9°. Dispersion is noticeable, r < v. The mineral is nonpleochroic. Chemical composition of the holotype sample is (wt %, electron microprobe data, H2O determined by thermogravimetry): MgO 1.12, MnO 0.10, FeO 3.15, CuO 8.98, ZnO 18.02, SO3 32.49, H2O 36.75, total 100.61. Its empirical formula calculated on the basis of 18 O apfu is: (Cu0.55Zn0.45)Σ1.00(Zn0.64Fe0.22Mg0.14Mn0.01)Σ1.01S1.99O7.98·10.02H2O. The structure was solved by direct methods and refined on the basis of 1797 independent reflections to R = 0.016. Belogubite is triclinic, P1̅ . Unit cell parameters are: a = 6.2548(1), b = 10.6112(2), c = 6.0439(1) Å, α = 82.587(1), β = 109.625(1), γ = 104.848(1)°, V = 364.81(1) Å3, Z = 1. The strongest reflections of the powder XRD pattern are [dobs, Å (I) (hkl)]: 5.73 (35) (100), 5.576 (47) (–110), 4.873 (100) (–111), 3.907 (31) (021), 3.719 (45) (0 –21), 3.229 (27) (111), 2.915 (25) (–221), 2.684 (26) (130). Belogubite is a new, CuZn-ordered member of the chalcanthite group having M1 cationic site preferentially occupied by Cu whereas M2 site is dominated by Zn with subordinate substitution of Fe2+ and Mg. The mineral is named in honor of Elena Vitalievna Belogub (born 1963), major researcher of the Institute of Mineralogy of the Urals Branch of Russian Academy of Sciences, Miass, Chelyabinsk Oblast, Russia, a well-known expert in the mineralogy of volcanic-hosted massive sulfide copper deposits of South Urals.
Marco E. Ciriotti

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Marco E. Ciriotti
Messaggi: 25818
Iscritto il: ven 25 giu, 2004 11:31
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Re: IMA 2018-005 = belogubite

Messaggio da Marco E. Ciriotti » mer 07 ago, 2019 15:01

Chalcanthite group

Belogubite (Cu0.5Zn0.5)(SO4)·5H2O tric P1 6.2548 10.6112 6.0439 82.587 109.625 104.848 1 364.81
Chalcanthite Cu(SO4)·5H2O tric P1 6.141 10.736 5.986 82.26 107.43 102.66 1 361.03
Jôkokuite Mn2+(SO4)·5H2O tric P1 6.37 10.77 6.13 98.77 109.97 77.83 1 384.9
Pentahydrite Mg(SO4)·5H2O tric P1 6.314 10.565 6.030 81.12 109.82 105.08 1 362.35
Siderotil Fe2+(SO4)·5H2O tric P1 6.292 10.632 6.072 82.62 110.01 105.18 1 367.98

Cranswickite Mg(SO4)·4H2O mon Cc 11.9236 5.1736 12.1958 90.00 117.548 90.00 4 667.04 is a related species.

NdR: alcune calcantiti ricche in zinco potrebbero essere ordinate e pertanto accreditabili a belogubite.
Marco E. Ciriotti

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