CUPRIFEROUS SANDSTONES
CUPRIFEROUS SANDSTONES, mostly mediumand fine‑grained rocks, composed of copper minerals: chalcosine, bornite, covelline (black copper), chalcopyrite, native copper, etc. C.s. are characteristic of arid lagoon‑delta deposits and are distinguished by greenish‑gray or gray colour against the prevailing brown and red background. C.s. also contain silver, sometimes rhenium, cobalt, vanadium, uranium, gold, and platinum. In Bashkortostan, C.s. are found in the Belebeyevskaya Upland and in the southern part of the Pre‑Urals foreland basin; they constitute a part of the pay streak stretching from the Orenburg Obl. through the south‑western areas of the RB to the RT and into the Vyatka Oblast. Intermittent C.s. deposits are 0.1— 2 m thick, they are accordant with stratification and build up ore zones 0.4—2 km long. The depth of C.s. occurrence is up to 100 m and more. In some places, there are several mineralized horizons; they occur horizontally or at an angle of 15—25°.
C.s. occur as covelline and malachite in the lenses of a coaly substance; as chalcosine, covelline, bornite, cuprite, tenorite — dispersed in the plant remains; as malachite – in the cement of greenish‑gray sandstones and conglomerates; as uniformly dispersed, invisible copper compounds — in bluish and greenish‑gray sandstone cement; and as nodules of chalcosine, malachite, azurite and couprite, paleyellow volborthite efflorescence (copper vanadate). Many C.s. mining sites were developed from the 18th century to 1914, the total area of approx. 4 thous. km2. The largest concentration of old mines is noted to the south and east of Belebey and around Kumertau. According to mountain cantons, the estimated copper reserves of C.s. within Bashkortostan exceeds 200 thous. t. Between 1960–91, ore manifestations of Kursak, Rudniki, Bakr‑Tau, Dedovo, Dmitriyevka, Malinovka, Yashlyarovo, Verkhotinka (Fyodorovsky Raion), Mikhailovskoye II, Stolyarovskoye and Tereklinskoye (Meleuzovsky Raion) were studied.
