Granit, ti ringrazio della risposta
Intanto ho trovato le due seguenti pubblicazioni a proposito dei giacimenti a REE:
- Rare Earth Minerals: Chemistry, Origin and Ore Deposits (The Mineralogical Society Series)

- VAN GOSEN B.S., LONG R.K., CORDIER D. & FOLEY N.K. (2010) The Principal Rare Earth Elements deposits of the United States - A Summary of Domestic Deposits and a Global Perspective [Kindle Edition] USGS Scientific Investigations Report 2010–5220, 96 pagg.
-CASTOR B.S. & HEDRICK J.B. Rare Earth Elements, 24 pagg. in "Industrial Minerals and Rocks"

Sulle pegmatiti due testi che mi sono stati consigliati sono:
-SIMMONS W.B., WEBBER K.L., FALSTER A.U. & NIZAMOFF J.W. (2003) Pegmatology: Pegmatite Mineralogy Petrology and Petrogenesis, Published by Rubellite Press, New Orleans, Louisiana, 176 pagg.
-LONDON D. (2008) Pegmatites Special Publications of The Canadian Mineralogist, vol. 10