Boevskite, Pb₄(TeO₃)₂(SO₄)(S₂O₃), the first mixed sulfate–thiosulfate mineral from the Boevskoe deposit, Southern Urals, Russia

The new mineral boevskite Pb 4 (TeO 3 ) 2 (SO 4 )(S 2 O 3 ) was found at the Boevskoe W-Be deposit, Chelyabinsk Oblast, Southern Urals, Russia.It occurs as very rare euhedral grains up to 0.25 mm at the contact of galena and pyrite, as inclusions in galena up to 0.2 mm, and as thin veinlets up to 0.2 0.03 mm filling cracks in sphalerite.Other associated minerals include anglesite, cerussite, chalcopyrite, empressite, hessite, ingodite, josite-B, matildite and pyrrhotite.Boevskite is colourless and transparent with an adamantine lustre.It is brittle, with uneven fracture.No cleavage or parting are observed.The Vickers' micro-indentation hardness (VHN, 10 g load) is 110 kg/mm 2 , corresponding to a Mohs' hardness of 2.5-3.D calc.= 6.599 g/cm 3 .Boevskite is optically biaxial, colourless and nonpleochroic.The mean refractive index calculated using the Gladstone-Dale equation is 2.08.The empirical formula