whether
these inclusions are solid needles or very fine tubular cavities, but
investigation indicated that they are probably elongated cavities with
a diameter of about 0.003 millimeters. It is doubtless the reflection
of the light from these different sets of rays which makes the six-ray
star visible in the cabochon cut gems. The cause of the inclusions
being arranged at angles of 60 degrees may bo looked for in the
hexagonal structure of quartz.
The
gems are cut in round cabochon shapes of standard sizes for the trade
and mounted in various articles of gold jewelry. They are sold under
the trade name starolite (not to be confused with stauro-lite), as well
as by the mineral name asteriated quartz. Messrs. Bell & Birkner
have had on exhibition a rough specimen of the asteriated quartz
weighing 10 pounds.
ROSE QUARTZ.
CALIFORNIA.
Mr.
M. J. Cooney, of Oroville, Cal., reports the discovery of rose quartz
by him near Forbestown, in the eastern part of Butte County, Cal. The
rose quartz occurs along the Mammoth gold lode. No information is
given regarding the quality.
RHODONITE.
MONTANA.
During
1914 a quantity of rhodonite was collected for ornamental use from the
dumps of the old Alice silver mine at Butte, Mont. Rhodonite occurs as
a gangue mineral at a number of the mines around Butte, and W. H. Weed
* states that, next to quartz, it is the most common gangue mineral of
the silver veins and is found in some of the fault veins of the copper
area. The rhodonite occurs with rhodocrosite and ore minerals in
parallel banded veins below the oxidized zone. In places veins composed
largely of rhodonite and quartz are 1 to 2 feet thick. Rhodonite is
found in other mines along the Rainbow lode and in the Allie Brown and
Wappello vein in the Lexington mine. During mining for metal ores a
quantity of rhodonite, along with other gangue minerals, has been
thrown on the dumps at the different mines, and the supply of this
material for ornamental purposes is now obtained by working over these
old dumps.
The
rhodonite forms fine compact even-grained masses of pale to deep pink
color. The best quality is bright rose-pink. Some of the massive
mineral is stained by seams of black oxides of manganese, which, by
their strong contrast with the pink, add to the beauty of the cut gems.
The Butte rhodonite is similar in character to that found at several
places in California, notably near Happy Camp, Siskiyou County, and in
the Indian Valley, Plumas County. During the last few years a quantity
of rhodonite from these different localities has been cut ana sold in
the west largely to the tourist trade, by which it has been very much
appreciated.
• Geology and ore deposits of the Butte district, Mont.: U. S. Geol. Survey Prof. Paper 74, p. 84,1912.
