A spectroscopic study of
blue radiation coloring in plagioclase
Anne M. Hofmeister and
George R.
Rossman
Division of Geological and Planetary Sciences
California Institute of Technology, Pasadena, CA 91125, USA
Abstract
Blue color in sodic plagioclase is produced by electronic transitions
of Pb in a manner
similar to the mechanism causing color in amazonite (potassium feldspar
colored blue-green
by Pb electronic transitions). The two blue feldspar varieties have the
following
characteristics in common: (l) elevated Pb concentrations (usually
greater than 0.01 wt.%),
(2) structurally incorporated H+, (3) similar
response of the color to heating and irradiation,
and (a) similar band shape, position, and polarization in the optical
spectrum