Abstract
The relevance of the work is due to the need to study ore copper-sulphide deposits in the Urals. Purpose of the work: description of accessory brockite in metasomatites of the Safyanovskoe copper-sulphide deposit. Research methodology: the chemical composition of minerals was determined using the Jeol JSM-6390LV scanning electron microscope with an INCA Energy 450 X-Max 80 energy dispersive attachment from Oxford Instruments (Institute of Geology and Geochemistry of the Ural Branch of the Russian Academy of Sciences, Ekaterinburg). Results and conclusions. For the first time for the Safyanovskoe copper-sulphide deposit (Middle Urals), an aqueous rare earth phosphate of calcium and thorium, brockite, has been determined; it belongs to the group of rhabdophane (Ca,Th,REE)[PO]4 ∙ _H2 O. The mineral is rare for the Urals and was described earlier in granite pegmatites of the Middle and South Urals, as well as in dikes of metaplagiogranites of the Bazhenov ophiolite complex. Brockite was found in the rocky metasomatites of the Safyanovskoe copper-sulphide deposit after crystalline lithoclastic tuff (tuffaceous sandstone) of acid composition. The main mass of the rock consists of quartz, kaolinite (sericite), carbonates (dolomite, Fe-magnesite) with rare inclusions of pyrite. Brockite is found in the dolomite-quartz matrix of the sample in intergrowths with REE-goyazite – strontium aluminophosphate. It is assumed for the Safyanovskoe copper-sulphide deposit that an alumina association with an ore mineral association and rare earth minerals, in particular, REE-alumophosphates and phosphates, will form closely at the same time as the temperature drops and the redox conditions of the mineral formation environment change.
Highlights
The Safyanovskoe copper-sulphide deposit is located 10 km northeast of the town of Rezh (Sverdlovsk region) and is confined to the southern part of the Rezhevskaya structural-formation zone
In a sample of wall rock metasomatites selected in 2017 in the face of a quarry at a depth of 200 m at the contact with massive pyrite-sphalerite-chalcopyrite ore, an aqueous rare-earth phosphate of calcium and thorium - brockite was discovered, which belongs to the group of rhabdophane (Ca,Th,REE)[PO]4×H2O
For the first time at the Safyanovskoe deposit, goyazite was described in association with barite veins in wall-rock sericite-pyrite-quartz metasomatites [5], and rare-earth goyazite in contact with Fe-magnesite was described in altered felsic volcanics [6]
Summary
The Safyanovskoe copper-sulphide deposit is located 10 km northeast of the town of Rezh (Sverdlovsk region) and is confined to the southern part of the Rezhevskaya structural-formation zone. At the contact with ore bodies, pyrite-chalcopyrite-chlorite-quartz and alunite (pyrophyllite) -kaolinite-sericite-pyrite-quartz metasomatites are developed [3]. In a sample of wall rock metasomatites (sample 3/17) selected in 2017 in the face of a quarry at a depth of 200 m at the contact with massive pyrite-sphalerite-chalcopyrite ore, an aqueous rare-earth phosphate of calcium and thorium - brockite was discovered, which belongs to the group of rhabdophane (Ca,Th,REE)[PO]4×H2O.
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