Grain-scale distribution of molybdenite polytypes versus rhenium contents: μXRD and EBSD data. (30th July 2019)

• Record Type: Journal Article
• Authors: Plotinskaya, Olga Y.; Shilovskikh, Vladimir V.; Najorka, Jens; Kovalchuk, Elena V.; Seltmann, Reimar; Spratt, John
• Is Part Of: Mineralogical magazine. Volume 83:Number 5(2019)
• Page Start: 639
• Page End: 644
• Publication Date: 2019-07-30
• Subjects: molybdenite, -- rhenium, -- EMPA, -- 3R and 2H polytypes, -- μXRD, -- EBSD, -- porphyry copper deposits, -- Urals; Mineralogy -- Periodicals; Mineralogy -- Great Britain -- Periodicals; 549.05
• DOI: 10.1180/mgm.2019.49
• Languages: English
• ISSNs: 0026-461X

Abstract

Abstract: Molybdenite from two porphyry copper mineralisation sites within the South Urals was studied by electron microprobe (EMPA), micro x-ray diffraction (μXRD) and electron backscattered diffraction (EBSD) methods. Elevated contents of rhenium (0.2 to 0.4, sometimes up to 1.1 wt.%) form linear zones from several to tens of micrometres wide and up to hundreds of micrometres long parallel to the elongation of molybdenite flakes. In most cases Re-rich zones are composed of the rhombohedral (3 R ) polytype of molybdenite, while the rest of the molybdenite flakes with ca. 0.1 wt.% of Re consist of hexagonal (2 H ) molybdenite. In rare cases Re-rich zones are confined to grain boundaries of molybdenite-2 H . It is shown that both μXRD and EBSD are the most appropriate tools to distinguish different polytypes within a single grain of molybdenite.