FRANCOLITE-GROUTITE ASSOCIATION. A NEW ORE MINERAL TYPE IN THE CARBONATITE ROCK ASSOCIATION

Abstract

Ore consisting primarily of francolite and groutite was found in Siberia in an ultramafic pluton consisting of alkalic rock and carbonatites. Groutite has not previously been reported in carbonatite complexes; the hand-books describe it as a rare mineral. The find of significant concentrations of manganese as groutite suggests that a new mineral type of carbonatite and apparently a new type of commercial manganese deposit is involved. The data indicate that ore zones that contain not only in the usual assortment of elements (Fe, Ti, P, Nb, Ta and RE) but also manganese, occur in ultramafic alkalic plutons in association with carbonatites produced in the volcanic and subvolcanic depth facies.