An
Investigation of Greenish Quartz found at the Thunder Bay Amethyst
Mine Panorama, Thunder Bay, Ontario, Canada, and Similar Localities
Laura J. BAKER
Greenish
quartz has been reported at a number of deposits throughout the world.
The material from Thunder Bay Amethyst
Mine Panorama is generally pale greenish gray. Samples of greenish
quartz
collected
from three other amethyst-bearing localities: Farm Kos and Farm
Rooisand,
Gamsberg Area, Namibia, are more intensely colored. The area between Kalomo
and Mapatiqya, Zambia, also produces greenish quartz. Quartz
from Southern Bahia, Brazil, is more
intensely green. Spectacularly green quartz is reported from Coos County, New Hampshire, USA.
A detailed
study of quartz from the Thunder Bay deposit shows that the
green quartz is part of a
color-gradational mineralization sequence involving
macrocrystalline
quartz of other colors and chalcedony.
For
all
localities, colors within the quartz are consistently correlated with
the
speciation of hydrous components, as darker green samples incorporate
larger
amounts of molecular water than paler greenish gray samples, colorless
samples,
and amethyst. The
appearance of strong
hydroxyl peaks in the infrared spectra is limited to amethyst and
colorless
varieties.