Formation of the Mount Weld rare earth element deposit, Western Australia: A carbonatite-derived laterite

Philip L. Verplanck; Jay M. Thompson; Cameron Mark Mercer; Ganesh Bhat; Heather A. Lowers; Adam Boehlke

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USGS · 70268378

Formation of the Mount Weld rare earth element deposit, Western Australia: A carbonatite-derived laterite

Philip L. Verplanck·Jay M. Thompson·Cameron Mark Mercer·Ganesh Bhat·Heather A. Lowers·Adam Boehlke

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Abstract

Carbonatite-hosted rare earth element (REE) deposits are the primary source of the world’s light REEs. The Mount Weld REE deposit in Western Australia is hosted in a lateritic sequence that reflects supergene enrichment of the underlying carbonatite. Water-rock interaction is a key to the formation of this world-class deposit. REE enrichment in the laterite is controlled by the breakdown of primary minerals, the release and transport of REEs, and the formation of secondary minerals. Secondary REE-bearing phosphate minerals are the primary REE-host phases in the laterite ore with monazite as the dominant phase; other REE-bearing phases include rhabdophane, cerianite, churchite, florencite, and crandallite subgroup minerals. Profiles through the laterite show that in the REE-rich zone, apatite and primary calcite and dolomite have broken down such that the loss of Ca and Mg, as well as Si and K, leads to a relative increase in the REEs. Sequestering of REEs in secondary mineral phases formed by groundwater further enhances the REE concentration.

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Source-reported bounding extent: -28.883149678371097° to -28.852849393633186° latitude; 122.51875238583227° to 122.5640779834194° longitude. This indicates report coverage, not an exact sampling location. View area on OpenStreetMap.

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Philip L. Verplanck, Jay M. Thompson, Cameron Mark Mercer, Ganesh Bhat, Heather A. Lowers, Adam Boehlke. 2025. Formation of the Mount Weld rare earth element deposit, Western Australia: A carbonatite-derived laterite. https://pubs.usgs.gov/publication/70268378

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