Small grains of accessory aeschynite in feldspar vein no. 31 of Vishnevye Mountains (South Urals) co-crystallize with late growth zones of feldspar crystals, as well as with ilmenite, titanomagnetite, muscovite, zircon, monazite, thorite, rutile, columbite and other minerals. Crystallization of aeschynite was followed by its metamict decay and formation of a nanocrystalline structure and further repeated dissolution and metasomatosis along microfractures of the mineral aggregate. Metasomatosis of aeschynite was accompanied by the formation of microporosity in muscovite-ilmenite aggregates at the contact with aeschynite grains.

Keywords: aeschynite, paragenesis, ontogenesis, metamict decay, metasomatism, microporosity, feldspar pegmatites.

Received 14.04.2022, accepted 30.11.2022

V.A. Popov, South Urals Federal Research Center of Mineralogy and Geoecology UB RAS, Ilmeny State Reserve, Institute of Mineralogy, Miass, Chelyabinsk oblast, 456317 Russia; popov@mineralogy.ru

I.A. Blinov, South Urals Federal Research Center of Mineralogy and Geoecology UB RAS, Ilmeny State Reserve, Institute of Mineralogy, Miass, Chelyabinsk oblast, 456317 Russia;

V.I. Popova, South Urals Federal Research Center of Mineralogy and Geoecology UB RAS, Ilmeny State Reserve, Institute of Mineralogy, Miass, Chelyabinsk oblast, 456317 Russia

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