Simmons WB, Falster AU
University of New Orleans, New Orleans, LA
McClure SF, Quinn EP
Gem Trade Laboratory, Gemological Institute of America
Carlsbad, CA 92008
George R. Rossman
Division of Geological and Planetary Sciences, California Institute of Technology
Pasadena, CA 91125-2500, USA
University of Manitoba, Winnipeg, Canada
Published in Gems and Gemology 39, 50-54.
A new variety of what was initially identified as pink beryl was
discovered in pegmatites a few km from Mandrosonoro, Madagascar. Chemical
analyses showed that this mineral contained up to 15.33 wt% Cs2O.
Structure refinements indicated that the Cs resides in the c-axis channel of the
beryl structure. Infrared and Raman spectra and x-ray powder patterns differ
from beryl due to peak shifts, new bands and missing bands. The structure and
chemical analyses indicate that the ideal formula is Cs[Be2Li]Al2Si6O18.
As such, this would be a new mineral that is a member of the beryl group. A
formal proposal for a new mineral name has been submitted to the IMA.
Irradiation experiments showed that the color is induced by radiation and lost
upon heating to 450 degrees C. Optical spectra show that the color is related to