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Vol. 3 (2000 year), No. 2

Liferovich R.P., Yakovenchuk V.N., Pakhomovsky Ya.A., Bogdanova A.N.
Crandallite group minerals of the Kovdor massif

The crandallite group minerals (CGM) from the hydrothermal assemblages occurring in the carbonatite-phoscorite complex of the Kovdor alkaline-ultrabasic massif have been studied. Goyazite, gorceixite and crandallite occur in low-temperature assemblages in cavities of the dolomitic carbonatites veins; crandallite has been identified also in the crust of weathering and in the carbonate-fluorapatite bearing breccia. The natural evolution of specie-forming cations in the order Sr-Ba-Ca has been shown on the basis of analysis of sequence of the described minerals crystallisation in the hydrothermal assemblages. SEM study has shown that crystalls of the studied phosphates are characterized by similar morphology of faces. Two generations of goyazite have been distinguished. Chemical composition data (microprobe analysis) and IR-spectroscopic data have been presented. Chemically all the described minerals are unique due to the lack of REE admixture. The conclusion about the importance of the CGM as a circumstantial evidence of secondary concentration of scandium and the possibility of scandium phosphates formation during low-temperature stages of hydrothermal mineralization has been made.

(in Russian, стр.10, fig. 5, tables. 2, ref 23, MS Word 95, MS Word 95 1170 Kb)