Goryainovite, Ca2PO4Cl, a new mineral from the Stora Sahavaara iron ore deposit (Norrbotten, Sweden). (2nd January 2017)

• Record Type: Journal Article
• Authors: Ivanyuk, Gregory Y.; Yakovenchuk, Victor N.; Pakhomovsky, Yakov A.; Panikorovskii, Taras L.; Konoplyova, Nataliya G.; Bazai, Ayya V.; Bocharov, Vladimir N.; Antonov, Andrei A.; Selivanova, Ekaterina A.
• Is Part Of: GFF. Volume 139:Number 1(2017)
• Page Start: 75
• Page End: 82
• Publication Date: 2017-01-02
• Subjects: Goryainovite -- new mineral -- halophosphate -- Stora Sahavaara iron ore deposit -- Sweden; Geology -- Scandinavia -- Periodicals; Geology -- Periodicals; 554.8
• DOI: 10.1080/11035897.2016.1227363
• Languages: English
• ISSNs: 1103-5897

Abstract

Abstract: Goryainovite, Ca2 PO4 Cl, is a new halophosphate, the chlorine analogue of 'spodiosite', Ca2 PO4 F. It is orthorhombic, Pbcm, a = 6.215(2), b = 7.011(2), c = 10.788(3) Å, V = 470.0(8) Å 3, Z = 4 (from powder X-ray diffraction data). The mineral is found in a magnetite-serpentine rock of the Stora Sahavaara iron ore deposit (67.408°N 23.297°E) where it forms small (up to 20 μm in diameter) rounded inclusions in magnetite, in close association with hydroxylapatite–chlorapatite, pyrrhotite, pyrite, chalcopyrite, valleriite and thorianite. Goryainovite is a transparent, colourless mineral with a vitreous lustre and a white streak. Cleavage is not observed, and the fracture is conchoidal. The Mohs hardness is c. 4. In transmitted light, the mineral is colourless, biaxial (–), β ≈ 1.66 (for λ = 589 nm). D calc = 2.98 g·cm −3 . The mean chemical composition specified with electron microprobe is (wt.%): P2 O5 33.19, Cl 16.96, CaO 53.25, O = Cl –3.83, total 99.57. The empirical formula calculated on the basis of 3 cations per molecule is Ca2.01 [P0.99 O3.98 ]Cl1.01 . The simplified formula is Ca2 PO4 Cl. The strongest X-ray powder diffraction lines [ d in Å, (I), ( hkl )] are 2.845(90)(113), 2.746(100)(211), 2.333(25)(114), 2.028(15)(132), 1.9569 (30)(115), 1.8370 (20)(025). The Raman spectrum of goryainovite includes 10 bands of -group vibrations. Goryainovite represents probably an early-formed phosphate of the magnetite-serpentine rock and crystallized together with magnetite. When chlorine fugacity decreased, almost all goryainovite was transformed into chlorapatite–hydroxylapatite, and only grains isolated in magnetite remained unaltered. The mineral is named in honour of Prof. Pavel M. Goryainov (b. 1937) for his contribution to the knowledge of the geology and petrology of banded iron formation of the north-eastern part of the Fennoscandian Shield.