This study shows the results of flotation concentration of mica minerals from kaolinised granite taken from the “Bašića bare” deposit – Kobaš, Srbac, The Republic of Srpska (B&H). Mineralogical composition of kaolinised granite is as follows: kaolinite, feldspar, quartz, and mica. After separating >0.630 mm, and <0.043 mm size class where kaolinite is concentrated, the rest is –0.630+0.043 mm class containing quartz, feldspar and mica. The mica concentrate was obtained by the flotation concentration, while feldspar and quartz were in the flotation underflow. According to the mineralogical analysis, the most abundant minerals are mica and chlorite/clays, while quartz and feldspar occur much less, and accessory minerals are represented in trace. The semi-quantitative mineralogical analysis obtained by the X-ray powder diffraction (XRPD) method of the mica concentrate amount to: mica ≈55%, chlorite/clays ≈35%, quartz ≈5%, feldspars (plagioclase and K-feldspars combined) ≈5%.

The article puts forward the thesis that the impressive achievement of Old Russian literature in the form of the literary heritage of St. Nil Sorsky is testimony to the creative continuation of Byzantine religious literature and the assimilation of the hagiographic stylistic patterns developed by the Veliko Tyrnovo School and its successors within the Eastern Slavic areas in the 14th and 15th centuries. The research is based on the texts: Admonitions for Spiritual Children and The Rule of Skit. Both are considered the most representative works of the spiritual leader of the Elders beyond the Volga. The analyses demonstrated the genre‑stylistic specificity of the above mentioned texts, expressing a Byzantine‑Slavic mystical discourse, one today known as Hesychasm. The text The Rule of Skit appeared to be unique in the history of East Slavonic utterances, presenting a comprehensive and integrated spiritual process leading to Hesychia. We are dealing with a treatise whose counterpart in Byzantine literature is The Ladder of Paradise by St. John of Sinai – this is a genre of Hesychastic literature, i.e. a kind of strategy for use in spiritual warfare leading from the state of sinfulness to deification, or holiness. In addition, attention has been drawn to the great care within the Hesychastes for the quality of texts expressing a mystical and ascetic current or serving liturgical purposes. New translations of Greek literature, which took into account the
achievements of the fourteenth‑century Hesychastic Councils and testify to the development of a philological and translation technique among the Orthodox Slavs, one that enabled the emergence of Slavic patristic syntheses, and to which St. Nil Sorsky’s works are recognized as the highest achievement.

During the Russian-Polish negotiations at the end of 1671 – the beginning of 1672, several Russian memorandums were handed over to Polish-Lithuanian diplomats. All these original documents are preserved in the Library of the Polish Academy of Sciences in Kórnik, Poland, and are studied as some of the most important forms of diplomatic communications between the Muscovite State and the Polish-Lithuanian Commonwealth. The memorandums clearly reveal the Muscovite diplomatic tactic against the Polish-Lithuanian side. They focus on the main problems of Russian- Polish relationships such as the transfer of Kiev from Russia to Poland (which had to be fulfilled in 1669 but which has never been executed), the policy towards the right-bank Ukraine hetman Piotr Doroshenko, who pledged his allegiance to the Ottoman sultan, the attack of the left-bank Ukrainian Cossacks (who were under the Thar’s rule) on the Lithuanian borderlands, and the implementing of the previous Russian-Polish anti-Ottoman treaty of 1667. It can be supposed also that the diplomatic form of the memorandum itself was borrowed by the Russian Foreign Office from the Polish-Lithuanian diplomatic tradition.