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In 1984, a new mineral ? yushkinite ? was discovered by a group of researchers under the supervision of A.B. Makeyev. The mineral was named in honour of the well-known mineralogist, honoured figure of RSFSR science, Professor N.P. Yushkin. At present, the mineral is known to be found in only one place ? Pai-Hoi anticlinorium in the middle reaches of the Silovayaha, in hydrothermal-metasomatic quartz-calcite veins of the lower coal rock mass of Serpukhov layer limestones.
Yushkinite is a mixed-layered vanadium mineral. Its structure, by analogy with the structures of other hybrid minerals ? valleriite, haapalaite, and tochilinite ? presents alternation of sulfide [V1-S] and "brucite" [(Mg,Al)(OH)2] packets. The mineral is found in the form of isometric flakes, 0.5-2 mm in size, and their aggregates, easily fissionable along perfect cleavage pinacoid planes. Its colour is pinkish-violet with a strong copper-purple and orange-red tarnish. The luster is metallic. Its hardness is less than 1. The density is about 3 g/cm3. Yushkinite is very stable in the natural environment. Under the influence of acids, the mineral is decomposed.
Twenty years have passed after the first description of the mineral (Makeyev and al., 1984), and we have got new data on the composition and characteristics of yushkinite and the minerals being in paragenesis association with it by modern methods.
As a result of this research, Yushkinite chemical composition and some characteristics have been specified, the mineral thermogram, new Raman and infrared spectra, which now can be used for diagnostic purposes, have been got by means of up-to-date devices.
Alongside with firm correlations between the components corresponding to the formula V1-S•n[(Mg,Al)(OH)2] in yushkinite, differences with significant variations of correlations between vanadium and sulphur and also between sulphide [V1-S] and "brucite" [(Mg,Al)(OH)2] components have been revealed. A new calcium variety of yushkinite (with 15 % of CaO), V0.84S•2.57[Mg0.50Ca0.25Al0.25(OH)2], has been identified. Thereby, the isomorphism limits of the mineral have been defined. It's possible to observe three types of isomorphism in relation to its formula V1-S•n[(Mg,Al,Ca)(OH)2]: 1) from VS to VS2 (K(1-x) = 0.50?1.13); 2) n (index with a brucite component) from 0.55 to 3.46; 3) formula index Ca2+ ? 0.01?0.25.
Thanks to the new research of yushkinite mineral paragenesis, the list of the minerals in its composition has been quadrupled. The new data on the relations of studied minerals have allowed us to overlook the mechanism of yushkinite formation. Owing to the data got, we have found out a new scheme of yushkinite formation reaction:
VS2 (patronite) + chlorite (amesite) + fluid V1-S•n[(Mg,Al)(OH)2] (yushkinite) + SiO2.
Yushkinite mineralization on the Silovayaha is known to be found in only one place in the world, and this place should be referred to the number of geological monuments with a limited collection material selection.
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