FRANCONITE, FIRST FIND IN THE USSR

Abstract

The Vishnevogorisk alkalic complex in the Urals is one of the mineralogically best studied complexes of such rocks in the USSR. More than 200 minerals (plus varieties) are now known here. In 1986, while studying mineralized fractures in miaskite, we identified four new minerals for this complex - ancylite, burbankite, donnayite and franconite, of which the last two are the first finds in the USSR and the second in the world. The optical properties of franconite were determined in immersion liquids. Individual single crystals form long blades. The chemical composition of franconite was investigated in detail. We may conclude that franconite occurs in appreciable amounts in the northern part of the Vishnevyye Mountains. Very likely it is also present in other alkalic rock complexes, where it overlooked in previous observations because of its macroscopically strong resemblance to zeolites and aragonite.