IMA 2016-063 = epifanovite

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Marco E. Ciriotti
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IMA 2016-063 = epifanovite

Messaggio da Marco E. Ciriotti » ven 12 gen, 2018 9:46

Referenza:
▪ Yakovenchuk, V.N., Pakhomovsky, Ya.A., Konoplyova, N.G., Panikorovskii, T.L., Mikhailova, Yu.A., Bocharov, V.N., Krivovichev, S.V., Ivanyuk, G.Yu. (2017): Epifanovite, NaCaCu5(PO4)4[AsO2(OH)2]·7H2O a new mineral from the Këster deposit (Sakha-Yakutia, Russia). Zapiski RMO, 146(3), 30-38.

Certamente questa descrizione-tipo, com'è giusto che sia, verrà poi ripresentata su qualche rivista in lingua inglese.
Si tratta di una specie monoclina con formula, NaCaCu5(PO4)4[AsO2(OH)2]·7H2O, del gruppo del lavendulano, prossima alla andyrobertsite (hydrated Na-analogue of calcioandyrobertsite; hydrated polymorph of sampleite).
Si presenta in incrostazioni formate da cristalli pseudotetragonali ("quadratici") molto piccoli (50 μm), vitrei, di colore turchese.

Le informazioni sulla struttura, gentilmente rimessemi da Sergey, sono qui: viewtopic.php?f=5&t=14171&p=244366&hili ... te#p244366
Marco E. Ciriotti

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

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Marco E. Ciriotti
Messaggi: 24371
Iscritto il: ven 25 giu, 2004 11:31
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Re: IMA 2016-063 = epifanovite

Messaggio da Marco E. Ciriotti » mar 16 gen, 2018 18:53

Grazie a uno dei co-autori ho ottenuto la pubblicazione. Qui l'abstract in inglese.

Referenza:
▪ Yakovenchuk, V.N., Pakhomovsky, Ya.A., Konoplyova, N.G., Panikorovskii, T.L., Mikhailova, Yu.A., Bocharov, V.N., Krivovichev, S.V., Ivanyuk, G.Yu. (2017): Epifanovite, NaCaCu5(PO4)4[AsO2(OH)2]·7H2O a new mineral from the Këster deposit (Sakha-Yakutia, Russia). Zapiski RMO, 146(3), 30-38.

Abstract:
Epifanovite, NaCaCu5(PO4)4[AsO2(OH)2]·7H2O, is a new natural arsenate-phosphate of copper, sodium and calcium. It was found in a quartz phosphate nest within greisenized cassiterite-rich granodiorite of the Këster tin deposit (Sakha-Yakutia, Russia). Mineral occurs as crusts of tabular pseudotetragonal crystals up to 50 μm across and 10 mm thick. Associated minerals are fluorapatite, pseudo-malachite, slavkovite, tobermorite, libethenite, arsenolite, native copper and unknown Mg-Zn phosphate. Epifanovite has a turquoise-blue color and pale blue streak. Luster is vitreous (dull in crusts). Mohs’ hardness is 3. Brittle. Cleavage is perfect on (001) and good on (100) and (010). Density measured in Clerichi solution is 3.65(3) g/cm–3, the calculated density is 3.73 g/cm–3. Optically biaxial (–), a = 1.708(5), b = 1.730(5), g = 1.735(5). 2Vmeas = 40—45°, 2Vcalc. = 50°. Optical orientation: X = a, Y = b. Empirical formula calculated on the basis of P + As = 5 is (Na0.94K0.06)S1.00
Ca0.82Na0.08)S0.90(Cu5.04Zn0.06)S5.10(PO4)4[(As0.81P0.19)S1.00(O1.92OH2.06Cl0.02)S4.00]·7.37H2O. The idealized formula is NaCaCu5(PO4)4[AsO2(OH)2]·7H2O. The Raman spectrum contain following lines: 293, 359 (v1—2, CuO5); 455, 556, 594, 640, 921, 962, 1002, 1086, 1153 (v1—4 PO4), 77, 121, 161, 183, 730, 828, 858 (v1—3 AsO4), 2900, 3200, 3410 (v1, OH) cm–1. The mineral is monoclinic, P21/m, a = 9.6912(9), b = 9.7440(9), c = 9.9561(9) Å, b = 102.23 (1)°, V = 918.7(1) Å3, Z = 2. Eight strongest lines in the powder X-ray diffraction pattern are (I—d[Å]-hkl): 100—9.73—001; 35—6.79—110; 12—4.355—021; 43—3.072—130; 24—3.061—221; 24—3.003—2 22; 11—2.698—023; 10—1.6775—504. The mineral is named in honor of the Russian geologist P.P. Epifanov, the discoverer of the Ege-Khaya and Këster tin deposits. Epifanovite is structurally close to lavendulan-group minerals and related species: andyrobertsite, calcioandyrobertsite, mahnertite and richelsdorfite.
Marco E. Ciriotti

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