New arsenate minerals from the Arsenatnaya fumarole, Tolbachik volcano, Kamchatka, Russia. XXI. Magganasite, CuFe³⁺₃O(AsO₄)₃

The new mineral magganasite, ideally CuFe 3+ 3 O(AsO 4 ) 3 , was found in the Arsenatnaya fumarole at the Second scoria cone of the Northern Breakthrough of the Great Tolbachik Fissure Eruption, Tolbachik volcano, Kamchatka, Russia.It is associated with sanidine, lammerite, paralammerite, johillerite, calciojohillerite, alarsite, hematite, tenorite, cassiterite, langbeinite, euchlorine, fedotovite, and wulffite.Magganasite forms prismatic crystals up to 0.2 mm long and up to 0.04 mm thick typically assembled in clusters up to 1 mm across.It is translucent, golden-or red-brown to brownish-yellow, with strong vitreous to semi-metallic lustre.D calc is 4.708 g cm -3 .In reflected light, magganasite is grey, weakly anisotropic.The reflectance values [R max -R min ,% (, nm)] are: 13.1-13.1 (470), 12.5-11.9(546), 12.2-11.9(589), 11.9-11.8(650).Chemical composition (wt.%, electron microprobe data) is: CuO 14.69, ZnO 0.06, Al 2 O 3 0.49, Cr 2 O 3 0.19, Fe 2 O 3 30.62,TiO 2 2.22, SiO 2 0.21, P 2 O 5 0.12, V 2 O 5 0.10, As 2 O 5 50.72,SO 3 0.63, total 100.05.The empirical formula based on 13 O apfu is Cu 1.22 Al 0.06 Cr 0.02 Fe 3+ 2.52 Ti 0.18 (As 2.91 S 0.05 Si 0.02 P 0.01 V 0.01 ) 3.00 O 13 .Magganasite is triclinic, P-1, a = 5.1813(7), b = 9.6427(11), c = 9.6834(11) , = 82.066(10), = 78.680(11), = 79.962(10),V = 464.41(10) 3 and Z = 2.The strongest reflections of the PXRD pattern