New arsenate minerals from the Arsenatnaya fumarole, Tolbachik volcano, Kamchatka, Russia. XVIII. Khrenovite, Na3Fe3+2(AsO4)3, the member with the highest sodium in the alluaudite supergroup. (18th December 2022)

• Record Type: Journal Article
• Authors: Pekov, Igor V.; Koshlyakova, Natalia N.; Belakovskiy, Dmitry I.; Vigasina, Marina F.; Zubkova, Natalia V.; Agakhanov, Atali A.; Britvin, Sergey N.; Sidorov, Evgeny G.; Pushcharovsky, Dmitry Yu.
• Is Part Of: Mineralogical magazine. Volume 86:Number 6(2022)
• Page Start: 897
• Page End: 902
• Publication Date: 2022-12-18
• Subjects: khrenovite -- new mineral -- alluaudite group -- arsenate -- crystal structure -- fumarole sublimate -- Tolbachik volcano -- Kamchatka; Mineralogy -- Periodicals; Mineralogy -- Great Britain -- Periodicals; 549.05
• DOI: 10.1180/mgm.2022.64
• Languages: English
• ISSNs: 0026-461X

Abstract

Abstract: The new alluaudite-group mineral khrenovite with the ideal, end-member formula Na3 Fe 3+ 2 (AsO4 )3 was found in the Arsenatnaya fumarole, Second scoria cone of the Northern Breakthrough of the Great Tolbachik Fissure Eruption, Tolbachik volcano, Kamchatka, Russia. It is associated with aphthitalite-group sulfates, badalovite, calciojohillerite, nickenichite, johillerite, tilasite, svabite, achyrophanite, ozerovaite, pansnerite, arsenatrotitanite, anhydrite, sanidine, hematite, cassiterite, rutile and pseudobrookite. Khrenovite occurs as coarse prismatic crystals up to 0.2 × 0.3 × 0.8 mm and their clusters up to 1 mm across. It is transparent, honey-coloured, red-, orange- or yellow-brown, with vitreous lustre. Khrenovite is brittle, cleavage was not observed. D calc is 4.257 g cm –3 . Khrenovite is optically biaxial (+), α = 1.825(7), β = 1.834(7), γ = 1.845(7) and 2Vmeas. = 80(10)°. The chemical composition (wt.%, electron-microprobe) is: Na2 O 11.47, K2 O 1.23, CaO 0.18, MgO 0.01, MnO 4.10, CuO 4.27, ZnO 1.99, Al2 O3 0.17, Fe2 O3 21.12, SiO2 0.08, P2 O5 0.01, V2 O5 0.10, As2 O5 56.03, SO3 0.02, total 100.78. The empirical formula calculated on the basis of 12 O apfu is (Na2.26 K0.16 Ca0.02 Mn0.35 Cu0.33 Zn0.15 Al0.02 Fe 3+ 1.62 )Σ4.91 (As2.98 Si0.01 V0.01 )Σ3.00 O12 . Khrenovite is monoclinic, C 2/ c, a = 12.2394(7), b = 12.7967(5), c = 6.6589(4) Å, β = 112.953(7)°, V = 960.37(10) Å 3 and Z = 4. The crystal structure was solved from single-crystal X-ray diffraction data with R 1 = 0.0287. Khrenovite is isostructural with other alluaudite-group minerals. Its structural formula simplified to the species-defining constituents is A (1) Na A (2)' Na M (1) Na M (2) Fe 3+ 2 ( T AsO4 )3 . The mineral is named in honour of the Russian volcanologist and geologist Anatoly Petrovich Khrenov (1946–2016).