Graduate
student Julia Goreva examined the cause of color of rose quartz. After studying
samples from localities throught the world, Goreva
finds that the color comes from pervasive rose-colored fibers of another
phase in the quartz. She has isolated and purified the rose colored fibers
from rose quartz from a number of localities worldwide, and has shown that
the optical absorption spectrum of the fibers is a close match to the optical
absorption pattern of bulk rose quartz. Scanning electron microscope images
of the fibers show that they can be on the order of 0.1 micrometer in diameter
and over 1 cm in length. Further details on the description of these fibers
and their properties are available at the web site of Julia
Goreva .
The X-ray diffraction and infrared absorption properties of the fibers
are similar those of dumortierite, but differ
in a number of fine details.
Post doc, Ma Chi, is characterizing these
fibers with transmission electron microscopy. The electron diffraction
patterns indicate that the fibers are a previously uncharacterized
mineral phase related to dumortierite. This work is discussed at the web
site of Ma Chi.
A structural model has been developed to interpret the lattice image photos
and unit cell constants of the new phase. It indicates that the fibers
have a structure which is based on a superstructure of dumortierite.
Light element analyses of the new phase with infrared spectra end electron energy
loss spectroscopy confirm that it contains the borate ion.