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TitreGeology and economic significance of selected rare earth element deposit types
AuteurSimandl, G J
SourceAbstracts of oral presentations and posters 2011; 2011 p. 59
LiensOnline - En ligne
Séries alt.Secteur des sciences de la Terre, Contribution externe 20120523
ÉditeurGouvernement du Québec
RéunionQuebec Exploration 2011; Quebec; CA; Novembre 21-24, 2011
Documentpublication en série
Mediapapier; en ligne; numérique
Sujetsgéochimie des terres rares; analyses de la roche, éléments de terres rares; carbonatites; pegmatites; prospection minière; géochimie; géologie économique
ProgrammeÉtude des gîtes des métaux rares, Initiative géoscientifique ciblée (IGC-4)
Résumé(disponible en anglais seulement)
The term "rare earth elements" (REEs) includes Y, Sc and the lanthanides (La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu). REEs are nearly as abundant in the Earth's upper crust as Cu, Pb, Mo, and Zn but they are generally more dispersed in rock-forming minerals. REEs are concentrated in a variety of settings including carbonatite-related deposits, peralkaline igneous complexes, peraluminous igneous complexes, pegmatites, metasomatic veins, iron oxide Cu-Au (IOCG) deposits, "ion adsorption clays" (weathered crusts overlying granitic rocks), and ocean sediments.
Since 1980's, China has become the dominant (>95%) producer of REEs. Currently, Bayan Obo (a carbonatite-associated Fe, Nb and REE deposit), together with two carbonatitehosted deposits in China, supply most of world's light rare earth elements (LREE). Mountain Pass (USA) is restarting production. China's adsorption clay deposits provide most of the heavy rare earth elements (HREEs).
To secure REE supply for its expanding economy, over last few years China introduced export taxes/quotas. This started REE price increases and world-scale REEs exploration rush.
Over 400 REE projects are active worldwide. Of these, 237 are grassroots, 135 have limited drilling, 42 are in the advanced exploration stage; 12 are in the pre-feasibility stage, 9 are at or near the feasibility stage and two operations are under construction (Intierra, 2011). The REE market is global. The ideal LREE and HREE development target would be located in a politically stable jurisdiction such as Canada, close to infrastructure and manpower, near surface, have acceptable grade and tonnage characteristics, favourable, or at least permissive, metallurgy and would not be located in an area that is environmentally sensitive or subject to First Nations objections.
Favourable market conditions, grade, and metallurgy permitting, REEs could also be derived as a by-product of phosphate fertilizer production or uranium processing. It is also possible that some REE-bearing fl uorspar deposits, Ti-Zr-bearing placers, and Olympic Dam-type (IOCG) deposits could enter into the supply-demand equation.
Discovery and development of a single giant, high-grade LREE deposit, such as Bayan Obo, or development of several typical carbonatite-hosted REE deposits outside of China would invalidate any projected medium- to long-term shortages of LREEs. Similarly successful development of HREE (± Zr, Nb, Ta, Be), peralkaline intrusion-related deposits such as Nechalacho (NWT) or Kipawa (Quebec) would represent signifi cant competition to Chinese ion adsorption clay deposits and would moderate HREE price fluctuations.