KARELIAN GARNET AS A PROMISING SOURCE OF SCANDIUM AND RARE-EARTH METALS

Abstract

Many garnet ore deposits and occurrences, in which at least 49.2 M t of pyralspitic garnet are concentrated, are located in Karelia in a favourable geographic, mining and economic environment. The study of the microcomponent composition of garnet shows that it contains high scandium and rare-earth metal (yttrium and lantanoids) concentrations. These elements are most abundant in metamorphogenetic garnet from sialic rocks. It contains commercial-scale scandium (Sc2O3 – 211–521 g/t) and promising secondary rare-earth metals concentrations (their oxide content is 245–608 g/t, in which the yttrium group contributes 85.5–99.8 %). Garnet contains more scandium than generally recognized scandium sources such as red sludge and silicate tailings in titanomagnetite ore processing. The predicted Sc2O3 resources of some garnet deposits and occurrences, varying from 0.7 to 695 t, are commeasurable with those of small deposits. The resources of geologically similar and closely-spaced localities in the Kem-Belomorsk group match those of a medium-size scandium deposit. To increase the ore base of rare metals, known garnet deposits and occurrences should be re-appraised and more localities prospected. Garnetiferous varieties of sialic rocks from the Belomorian complex seem to be the most suitable for priority prospecting and appraisal. The microcomponent composition of garnet ore in mafic rocks should be studied. There are some objective prerequisites for commending Karelian garnet as a new promising complex non-radioactive source of scandium and secondary rare-earth yttrium-group metals. Further comprehensive geological and technological study of garnet localities is needed to provide arguments in favour of the possible use of Karelian garnet as the ore of these metals.

Keywords

• гранат
• редкие металлы
• редкоземельные металлы
• скандий
• иттрий