1london Granitic Pegmatites- Scientific Wonders and Economic Bonanzas

Granitic Pegmatites: Scientific Wonders and Economic Bonanzas

Pink pezzottaite crystal, 1.2 cm long, from Ambatovita, Fianarantsoa Province, Madagascar. The rim of the crystal is white beryl with minor microcrystals of milarite and bavenite. Named in honor of Federico Pezzotta. Photo Matteo Chinellato

David London1 and Daniel J. Kontak 2 1811-5209/12/0008-0257$2.50  DOI: 10.2113/gselements.8.4.257

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ranitic pegmatites have been a focal point of research by petrologists and mineralogists for over a century. Mineralogical interest stems from the diversity of rare minerals that some pegmatites contain. Petrologic efforts are aimed at resolving the processes or agents that produce the complex textures and spatial heterogeneity that distinguish pegmatites from granites. Much of the scientific study of pegmatites has been motivated by exploration for the economic commodities they provide. Pegmatites yield quartz, feldspars, and micas for industrial uses; strategic rare metals for electronic, aerospace, and energy applications; and many of the world’s finest gem and mineral specimens.

synonymous with a granitic composition. The bulk compositions of pegmatites plot close to the thermal-minimum composiKeywords : pegmatite, granite, rare metals, industrial minerals, gemstones tion in the granite system, which includes rocks with nearly equal INTRODUCTION proportions of quartz, sodic plagioclase, and potassic Pegmatites are texturally distinct variants of the more (alkali) feldspar. Only a small proportion of pegmatites common and more voluminous plutonic igneous rocks, (