Iowa County democrat. [volume] (Mineral Point, Wis.) 1877-1938, 1908-10-08

Sterrett, of the United States geOlOgi-
cal survey, whose statistical report on
the precious stones OF this country
as an advance chapter from Mineral
tResources of the United States. Cal
ander Year 1907" Two large com
panies operated mines containing blue
sapphire in its original matrix, and
two other large companies and smaller
or individual producers worked auri-
ferrous placer deposits containing warn
colored spphires. The blue sapphire
in matriX wa worked in the judith
river region in Fororrs County, at
points about II and 10 miles west
southwest of Utica; the placer de
posts were worked at the head Of
Dry Cottonwood creek, in Deerlodge
county. The auriferous placer de-
posts along Missouri river below
Helena, once so extensively worked
also yielded a few stones during 1907
The blue sapphires of Fergus county,
often called YOgO sapphires, range
in size from minute crystals up 20
those of 4 or 5 carats. Rarely crys-
tails of or 10 carats are founr but
the greater number weigh under 3
carats. A large quantity of small
saphires, classed as culls, is also OBJ
tanned. This material is in great de-
mand for watch jewels. the flattened
form Of many Of the crystals render
ing them specially suitable for this
purpose. In color the Yogo sapphires
range from light blue to the rich
'cOrnfoWer" blue characteristic oil
the oriental sapphire. They make
beautiful gems and are highly priced
for their color and brilIiancy. PROP
ably over 80 per cent of the sapphire
lis Of good blue color and OF gem
quality Occasionally purplish gems
are found.
The auriferous placer eposits on
Dry Cottonwood creek are located al
an elevation Of 5000 feet, nearly 1,50O
feet above the valley of DeerIodge
river, to which the creek is tributary.
The gravels in the gulches are from
10 to IA feet thick and the beds are
| from 40 to 100 feet wide The gold
carried by the gravels and recovered
from the concentrates is mostly fine,
although nuggets worth several dol
, lars are said to have been found 1t
! is claimed that the value of the gold
recovered is sufficient to pay OperaL
! ing expenses. The larger part of the
, sapphires Of this locality can be used
for mechanical purposes only, but
some of the crystals are suitable in
size, color, and quality for cutting II
these sap9hires are deep and light
aquamarine and pale yellowish green.
/ Other colors are clear and smoky
/ blue, light and dark topaz yellow,
straw yellowish green, and light and
dark pink. Some stones are nearly
ruby red, lilac, and pale amethystine.
and some are coIorless. It is not IN
usual to find aquamarine coIored
stones with pink spot in the center
"a combination trat furnishes an at
i tractive gem when cut. The deep
pink sapphires are particularly rich
and beautiful under artificial light,
even when not very attractive in ma
/ tural light
! A brief account Of the Montana sap
phire mines is given by Douglas B.
Sterrett in a paper on the production
Of precious stones published by the
United States Geological survey as
an advance chapter from Mineral
Resources Of the United States, Cal
endar Year 1907" Copies Of this pa
I per may be obtained by applying to
the director Of the survey at Wash
ington.