Montana oil and mining journal. [volume] (Great Falls, Mont.) 1931-1953, 1941-11-22
PHOTOGRAPHY
OF ARTICLES
ON CHROMITE
Continued from Page Five)
Montana chromite deposits, largest
in North America: MineralOgist,
o n


Montana chromite deposits, largest
in North America: MineraIOgist,
vol 3, No. 6, PIP. rs, 1928, 1895
(micrOfiIm).
Mr. A. Martin discovered chromit
IN the Beartooth mountains in 1905
Little Importance was attached to tn
discovery until war broke out thel
Martin was commissioned to continue
prospecting for chromite Great lense
of chromite were traced for 30 mile:
through the Beartooth mountains II
Carbon county, and other deposit!
were found in saltwater. Sweetgras.
and Madison counties. Chromite L
found in ultra-basic rocks which in
trude porphyries and mica schists
Minerals found associated with the
chromite: gold and silver ores, copper
and iron, molybdenite, steatite and
serpentine.
Schafer, Paul A. Chromite de-
pOsits of Montana: Montana Bur.
Mines and Geology, Mem. Is, IS
PIP, pIs., IL figs, 1887.
Chromium bearing rocks are found
in Sweetgrass, Saltwater, Park, Car
bon and Madison counties. Most i'm
portant district is in the Beartooth
range north of Yellowstone national
park. The Saltwater igneOus complex
is the name applied to a great ultra
basic sheet exposed between Boulder
valley, IA miles south of Mcleod, and
Little Rocky creek, six miles southwest
of Dean. The Saltwater igneous sheet
lies between Paleozoic rocks and older
e-Cambrian formations. Rocks COM
posing the sheet are: anorthosite,
gabbro norite, bronzitite, harzburgite,
and related ultra-basics. Minerals
present are small percentages of plat
mum and palladium, chalcopyrite,
pentlandite and pyrrhotite, with bands
Of chromite in the harZburgite. The
Saltwater chromite belt is separated
into four segments with natural geo.
graphic boundaries: the Boulder area,
Iron Mountain area, West Saltwater
area, and the Saltwater area. The ore
in the Saltwater complex deposits
would run from 20 to 40 percent Cr2
O3, depending on the sorting and mill
ing methods used. The chromite- bear
ing peridotite extends for a length Of
q miles, and has an estimated re-
serve Of 10000 600 tons Of possible ore
and 100000 tons of speculative ore.
The Red Lodge chromite area is from
IL to 20 miles south of Red Lodge, in
geological surroundings quite foreign
to those near the town of Red Lodge.
The igneous and metamorphic Sc
quence of the area consists of pre-
Cambrian amphibole and chlorite
schists; eulysitic rocks, gabbro, peri
dotite, chrome-serpentine rocks; peg
Matte and porphyries. The deposits
are found in the Hellroaring group, |
High Line deposits, Edsel, Four
Chromes, and Little Nell group. The |
ore in this Red Lodge area is low /
grade The great complexity of struc-
ture, especially faulting, on Hellroar-
ing and Line Greek plateaus would
add materially to the cost and diff
Guilty of development and mining The
Sheridan deposits are exposed between
Horse creek and Ramshorn creek about
d miles east Of Sheridan, Madison
county. The country rocks are of the
Cherry creek series and the chromite
occurs as lenticular masses or segre-
cations in a series of diorite bikes.
One dixie asSayed Al percent Ora O3.
Continued Next Week.