Prices.—Pure
crystalline quartz for use in the manufacture of pottery, abrasive
soaps, paints, wood fillers, etc., brings usually from about $2 to
$3.50 per long ton, crude, f. o. b. quarries, and the ground material
brings from $6.50 to $10 per short ton f. o. b. mills, the price
varying with fineness of grinding, distance from markets, etc. The
purer varieties of quartzite used for similar purposes and for
sandpapers sell, as a rule, at somewhat lower prices, the crude
bringing from about $1 to $2 per long ton f. o. b. mines, and the
ground from $6 to $8 per short ton f. o. b. mills. The finest grades of
crystalline quartz ground to an impalpable powder and used for tooth
powders, etc., may bring as high as $20 per ton f. o. b. mills.
Imported French flints cost from $3.50 to $4 per long ton f. o. b.
Philadelphia, and can be delivered in Trenton, N. J., for less than $5
per long ton.
SMOKY QUARTZ.
Smoky
quartz has somewhat the appearance of smoked glass, though varying from
a faint tint of gray or yellowish brown to nearly black. The shade
commonly varies considerably from point to point in the same crystal.
Transparent
crystals have been found in a number of the pegmatite masses of Maine
and some are of value as museum specimens and as gems. In 1884 a mass
weighing over 6 pounds, with clear spaces several inches across, was
found on Blueberry Hill in the town of Stoneham, Oxford County, and a
broken crystal that weighed over 100 pounds and another 4 inches long
and 2 inches across, very clear in parts, were found near Mount
Pleasant in Oxford County. On the southwestern slopes of Mount Apatite
in Auburn, Androscoggin County, a large pocket in coarse pegmatite has
yielded considerable quantities of fine crystals. Transparent quartz of
pale amber-brown color has been observed by the writer at the Berry
quarry, a short distance south of Mount Apatite in Poland, one mass
showing a clear portion 3 hx 5 inches in size.
The
nature of the coloring matter is not known, but on heating the smoky
varieties generally become first yellow and finally colorless. Some
yellow quartz produced in this way is cut as a gem under the name of
"Spanish topaz" or "citrine," though the true citrine is a natural
occurrence of transparent yellow quartz. Crystals or irregular masses
of transparent smoky quartz found in any of the feldspar or gem
quarries should be preserved, for the}r may prove of value and interest to the mineral or gem collector.
ROSE QUARTZ.
Most
of the rose quartz found in Maine is somewhat paler in tint than that
commonly utilized as a gem stone, though occasionaiiy some of deeper
tint is obtained. The principal supplies of this mate-
