The Serra Verde lateritic REE deposit

The Serra Verde deposit in the Goiás Province of central Brazil is rich in recoverable rare earth elements (REE). We are developing a formation model for the deposit and investigating its potential for REE extraction. 

The Serra Verde deposit has an inferred resource of 458 million metric tonnes at a grade of 0.098% total rare earths (May 2012, 43-101 compliant). Heavy rare earth elements (HREE) account for 24% of the deposit.

The REE occur in a typically 6m-deep layer of clay-bearing saprolite produced by the deep weathering of granite. Initial testing suggests that more than 50% of the REE bulk are sorbed on clay and can be recovered by a simple elution process.

Project details

The Serra Verde project will develop a model for the introduction, enrichment and mineralogical residence of REE at the Serra Verde deposit. We aim to:

  • establish links between multiple magmatic events and REE introduction
  • determine and quantify the processes leading to REE enrichment
  • assess the effect of tropical weathering on REE grades and distribution
  • identify the residence of REE in primary, secondary and supergene minerals

Serra Verde Mining are supporting a PhD project undertaken by Carmen Pinto-Ward, co-hosted at the Museum and Imperial College. Contact for details. 

Deposit formation

The Serra Verde REE deposit is associated with a Proterozoic alkali granite within the Goiás province of Brazil. The REE introduction and enrichment may be related to three main stages of geological evolution: 

  1. Emplacement of the Pela Ema tin granites (~1.8 Ga). This resulted in the formation of typical tin-bearing greisen veins hosting monazite and xenotime.
  2. Intrusion of an evolved alkaline (carbonatite?) complex at depth (~540 Ma).This caused potassium metasomatism (K-feldspar-biotite) with additional introduction or recrystallisation of monazite, xenotime and magnetite.
  3. Miocene(?) lateritisation. 

A 30-35m-thick lateritic weathering profile developed, resulting in breakdown of feldspars to clay and dissolution of REE-bearing minerals with reprecipitation in the saprolite ore zone. Colluvial accumulations of REE are also present.

Project details

Imperial College
Serra Verde Mining LLC

Serra Verde Mining LLC