of a bluish gray or buff color. The red variety, carnelian, and the
green variety, chrysoprase, have not been found in Arizona. It is
formed in rock cavities, and found in place or in sands and gravels.
A variety of chalcedony known as "turtle-back" or moonstone has
been found here. It shows a peculiar mottled appearance, when cut,
resembling the back of a turtle. Chalcedony is often called moon-
stone when cut, but improperly so.
Amethystine Quartz: Amethystine quartz is a clear purple col-
ored quartz. The best known occurrence is in the McConnico dis-
trict. According to the Mineral Resources of the United States
for 1908, one crystal from this district was sold to Tiffany, of New
York City, for $59.00. The great objection to it as a gem is
that it loses color. It is found in veins and vugs, often with silver
and lead ores.
Diamond: The only diamonds found in Arizona are meteoric,
and occur in meteoric iron found at Canyon Diablo, near Coon
mountain, in the northern part of the state. The crystals are very
small, and have no commercial value.
At one time, in 1870, a company was organized for the explora-
tion of diamonds and other gems in Arizona and New Mexico.
A great quantity of gems said to have been found in these fields was
exhibited, and expeditions to the locality gathered approximately
6000 carats of rubies and 1000 carats of diamonds.
Topaz: Topaz is a fluo-silicate of aluminum, usually clear and
colorless, but most valuable when golden yellow1 or blue in color.
It is found in the northern part of Arizona. The golden yellow var-
iety is very apt to fade.
METHODS OF EXTRACTION AND PREPARATION.
Most of the gems and precious stones found in Arizona are merely
by-products of the mining of other substances, and are sorted out
from poorer specimens. The turquoise, garnet and peridot are mined
separately. There are several companies that have produced tur-
quoise in Arizona. The garnets are gathered from the sand and
gravel beds in which they are most commonly found.
In preparing precious stones for market, the best specimens are
first selected, cleaned, cut in various shapes, and polished. Poorer
specimens are also cut and polished, or they may be reserved for use
in private and public collections.
