Mineral Sciences Staff
- Michael A. Wise
- Geologist, Division of Mineralogy
- Phone: (202) 633-1826
- Fax: (202) 357-2476
- E-mail Address: wisem
- Mailing Address:
PO Box 37012, MRC 119
Washington, DC 20013-7012
- Shipping Address:
National Museum of Natural History
10th & Constitution NW
Washington, DC 20560-0119
- Ph.D. University of Manitoba (1987)
- Mineral Dependence - Gemstones to Cellphones (Q?rius Webcast)
The global exploitation of granitic pegmatites (exceptionally coarse to gigantic-grained igneous rocks) as major sources of industrial, technological and gemological materials, require that we have a strong understanding of the processes that generate them. Pegmatites are important sources of rare-elements, and when present in economic quantities, these elements may be extracted for use in a wide range of technological applications, such as lightweight alloys, nuclear engineering and electronics (beryllium); ceramics, pharmaceutical products, lubricants, and lithium-batteries (lithium); electronic capacitors, jet engines and prosthetic devices (tantalum); magneto hydrodynamic electric generators, biological and medical research (cesium); and integrated circuits and light-emitting laser diodes (gallium). The industrial minerals, feldspar and quartz, are extracted from pegmatite deposits for use by the glass and ceramic industries, while mica is used in construction materials, cosmetics, paints and insulation. Some of the world's best-known gem materials (e.g., aquamarine, emerald, sapphire, topaz, and tourmaline) are obtained from pegmatite deposits.
Pegmatite research in the Department of Mineral Sciences focuses on three broad, but closely linked disciplines, which are the basic research components necessary for a full understanding of the pegmatite-generating process.
Crystal chemistry and crystal structures of pegmatite minerals
Basic mineralogical studies carried out on major and accessory pegmatite minerals include: the solution and refinement of crystal structures, investigation of structural states (e.g. order-disorder) in minerals, and the effects of "pegmatophile" elements (e.g. Rb, Cs, Li, B) on mineral structures.
Petrology and geochemistry of pegmatites
Petrographic study of pegmatite textures is fundamental to understanding the nucleation and growth of giant crystals. Multi-generations of tourmalines, feldspars, micas, garnets, and Nb-Ta oxide minerals are typical of many chemically evolved pegmatites and the minor and trace element signatures of these minerals help to decipher changes in melt and fluid composition during pegmatite consolidation.
Evolution of granite-pegmatite systems
Field-based studies of the internal zoning of individual pegmatites, the regional zonation of granite-pegmatite systems and the global relationship between pegmatites and broad geologic and tectonic settings helps provide a better understanding of the processes responsible for pegmatite generation and can provide important information on the chemical evolution of the earth's crust.
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