The morphology and anatomy of a paragenetic intergrowth of REE minerals (xenotime and forencite) from veins of Svodovy Au-REE occurrence (Subpolar Urals) are described. The sequence of crystallization of minerals is identifed using the features of internal structure of individuals and aggregates: surfaces of diferent types, sector boundaries and oscillatory, trend and sectorial zoning. Evidence for a HREE-to-LREE directive crystallization of REE phosphates is given. The linear and volumetric rates of face growth are analyzed. The mechanisms of crystal growh and formation of zoning and surfaces of joint growth of sectors of diferent faces are discussed. The crystals are studied using an original method of analysis of mineral aggregates with oscillatory zoning.

Figures 9. Tables 2. References 21.

Key words: anatomy of crystals, oscillatory zoning, xenotime, forencite, REE fractionation, Subpolar Urals.

S.A. Repina, South Urals Research Center of Mineralogy and Geoecology UB RAS, Institute of Mineralogy, Miass, Chelyabinsk oblast, 456317 Russia; repina_sa26@mail.ru

V.A. Muftakhov, South Urals Research Center of Mineralogy and Geoecology UB RAS, Institute of Mineralogy, Miass, Chelyabinsk oblast, 456317 Russia; 
South Urals State University, Miass Branch, ul. 8 Iyulya 10, Miass, Chelyabinsk oblast, 456304 Russia

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