Components of lithium depletion from starting spodumene—petalite assemblages in subsolidus evolution of Portuguese pegmatites

Abstract

In Portugal, especially in the NW region, mineral assemblages with spodumene after petalite and petalite only are hosted in pegmatite bodies, which intrude metasedimentary to metavolcanic, Silurian, or earlier formations. Regardless of the region in which they occur, this paragenesis and the pegmatites that support them are affected by evolutionary trends of deuteric to supergenic alteration that may lead to lithium leaching and severe depletion of early contents sequestered in starting materials. That has relevant consequences for the recovery of Li resources, not only by the generalized lowering of the Li grades of pegmatite deposits but also by the multiplication of Li-specific carrier phases, which penalizes the recovery percentages during any mineralurgy routines. Predictably, recovered grades will be significantly lower than those obtained by chemical analysis of whole rock and channel pegmatite samples.