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Published October 1991 | public
Journal Article

Origin of color in cuprian elbaite from São José de Batalha, Paraíba, Brazil

Abstract

Gem-quality elbaite from Paraíba, Brazil, containing up to 1.4 wt% Cu has been characterized using optical spectroscopy and crystal chemistry. The optical absorption spectra of Cu^(2+) in these tourmalines consist of two bands with maxima in the 695- to 940-nm region that are more intense in the E ⊥ c direction. The vivid yellowish green to bluegreen colors of these elbaite samples arise primarily from Cu^(2+) and are modified to violetblue and violet hues by increasing absorptions from Mn^(3+).

Additional Information

© 1991 Mineralogical Society of America. Manuscript received July 16, 1990. Manuscript accepted May 21, 1991. The authors wish to thank Gerhard Becker, Friedrich August Becker Edelsteinschleiferei, Idar-Oberstein, Germany, and Brian Cook, Nature's Geometry, Graton, California, for providing samples and information on the deposit shortly after its discovery. David Stanley Epstein, Precious Resources Ltda., Teόfilo Otoni, Brazil, provided useful information on the deposit, and Rock Currier from Monrovia, California, provided additional study material from this locality. Preliminary spectroscopic investigations were done by Mike Moon and Meredith Mercer, and the optical properties were measured by John I. Koivula and Christopher P. Smith, all from the Gemological Institute of America (GIA) or the GIA Gem Trade Laboratory, Santa Monica, California. X-ray crystal alignments were performed by William P. Schaeffer, and electron microprobe analyses were obtained by Paul Carpenter and John Armstrong, all with the California Institute of Technology, Pasadena, California. X-ray powder patterns were obtained by Waldo Winterburn, Center for Materials Research, Stanford University, Stanford, California.

Additional details

Created:
August 22, 2023
Modified:
October 26, 2023