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Page: of 12
The Nevada
The Idaho-Maryland vein, which has an average dip of
about 70° S,, had been worked toadepth of 2000 feet prior to 1919.
In 1919 Mr. Errol MacBoyle was operating the Union Hill Mine.
The Idaho-Maryland Mine was idle and full of water to within
twenty-five feet of the collar, Mr. MacBoyle, during this time,
and previous to 1919, was instrumental in the consolidation
of the Union Hill and Idaho-Maryland; and by the end of 1919
the company known as the Idaho-Maryland Mines Company had
acquired 676 acres of mining property. J. A. Fulton, representing the Bulkeley Wells interests, was placed in charge of the
Idaho-Maryland Mines Company in 1919 and served inthe capacity
of manager until February, 1924, when Mr. M, A. Roche was
appointed as his successor. The Union Hill Mine was allowed to
fill with water shortly after Mr. Fulton took charge, and the
dewatering of the Idaho-Maryland Mine was undertaken. Unwatering continued until June, 1921, but it was carried on in
conjunction with repairing of timber, etc. New development
work and repairing of old drifts have been carried on extensively
for the last three years. Some 25,000 feet of drifts and crosscuts have been driven, and over 10,000 feet of drifts and crosscuts have been opened up and repaired. The deepest level of the
mine is 2500 feet vertically below the surface, or approximately
sea-level, The mine employes average about 140 men per day.
The surface is equipped with a twenty-stamp mill and
concentrating plant. The domestic water supply for offices and
mill is brought through a twenty-two-inch steel pipe-line for
over two and one-half miles, The water is taken from one of the
high line canals of the Pacific Gas & Electric Company. To
comply with the requirements of the State Debris Commission,
a rock dam has been constructed across a small ravine; and
the tailings from the mill are thrown behind this dam and allowed
to settle. Previous to this construction, the tailings were allowed
to flow down the creek, The power to operate the mine machinery is also received from the Pacific Gas & Electric Company.
The main shaft is equipped with two two-ton skips, which are operated in counterbalance. The motive power consists of one
300-horse-power motor directly geared to the rope-winding
drums,
The development work at present consists of sinking prospect winzes, driving drifts along likely-looking contacts, and
cross-cutting, to great distances, both the hanging-wall and the
foot-wall formation. The mine has in operation three electric
hoists and four air hoists. The broken rock, previous to June,
1924, was transported from the 2000 level through the Canyon
shaft to the 1000 level, a slpe distance of 2089 feet. Here the
rock was dumped into chutes and hauled to the main-shaft
ore and waste pockets. From these pockets the ore and waste
were hoisted directly to the surface in skips which automatically
dumped their contents in bins built within the head frame at
the top of the shaft. The rock from here is loaded into cars and
pulled by means of a gasoline engine either to the mill ore bins
or waste dump, according to its classification. The Conyon
shaft, after June, was discontinued, and the ore and waste are
now pulled directly from the 2060 level to the surface without
rehandling. Electric: storage batteries and trolley wires are
used for transporting the ore on the 2000 level.
About 40,000 gallons of water is pumped from the mine
daily by both electric and air-driven pumps, The water is pumped
from the mine in four independent steps or stages.
"In none of the foregoing mines has there been any appreciable diminution in the tenor of the ore, at the great depth reached;
in fact, the Pennsylvania ledge. where it has recently been
developed in both the Empire and North Star workings, is as
rich as in any of the upper levels. The Empire has also developed large bodies of high-grade ore in its lower levels,
Therefore there seems to be little doubt that the ore-shoots
in the Grass Valley district will continue in depth to the limit
of economical handling."
Recent developments in the lower levels of both the North
Star and the Empire show large ledges of good paying ore;
they are now down a mile and a quarter and are still going
deeper in good milling ore.
(To be continued next week)
County Nugget Wednesday, June 7, 1972 7
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