The Anaconda standard. [volume] (Anaconda, Mont.) 1889-1970, 1899-12-26
MINING BRIEFS.

Joplin, Mo, ore averages Is per cent.
zinc and 4 per cent lead. The aver
age cost of mining and hand jigging
free ore that needs no crushing is Sill
cents per ton. Thirty tons of ore make
As tons zinc concentrates and IL tons
lead, making the cost per ton of clean
ore $4.27. The present price of stand
ard 60 per cent. zinc ore at the mine
is $35 per ton, lead ore $53 per ton.
The Broken Hill mine. New South
Wales, is officially reported to have
produced since it's discovery 4,132, iS4
tons of ore, containing 1891, 1863 tons OF
lead and 100,159,76S ounces of silver,
the total value of which is about $780,
O00,0 900 The expense of production was
about ST., 900, 900, and nearly S35, 100000
have been disbursed in dividends.
Speaking of dredges, the Denver
Mining Reporter says: Two different
kinds of machines are now in use. One
brings the material to the surface by
means of buckets on an endless chaln,
the other by means of shovels. Both
are said to work well. The machines
now in use are operated by steam pow
er. but those in course of construction
are to be run by electricity.
The Mining Investor says that the
Gold Coin at Victor, Colo, is leading
the procession in the way of output at
present. From the office of the COM
pany it is learned that 1870 tons is now
being produced every "a hours. One
hundred tons of this is of second smelt-
ing grade, while the remainder of the
output is sent to the Economic mill
owned by the Woods people
The south end or Gold Hill mines of
the Comstock are the scene of consd-
,,1o NT,1n work is in nr0u-
ress at the Belcher. the Challenge
Jacket Imperial. the Overman and he
Caledonia It was in the Belcher and
the Crown Point which adjoins 1t that
the first big Comstock bonanza was
found. and it was this bonanza that
inence.
The. diamond mines of South Africa
at Kimberley, which were originally
worked by an extensive open cut sys-
tenn, which became eventually very eX-
pensive and dangerous, are now work
ed by levels through vertical shafts
sunk back from the rim of the pits
The system of mining is similar in some
respects to that at drift mines in Cal
ifornia But one level is worked at a
time, which, when worked out, is aban-
doned and another level IS opened
The De Beers mine is opening the l4oo
level The main levels are 200 feet
apart. AS the workings proceed down.
ward the excavation fills from the sur
face by caving of the rim of the era
ter-like excavation At the kimber-
ley mine the skip is filled, hoisted 1920
feet and dumped in 45 seconds. The
skip contains four tons of diamond
bearing earth.
The Mining and Scientific Press says:
There is a limit to the depth of pos
sible ore formations, as that formation
is dependent on the presence of water
AS one sinks into the earth, tempera-
ture increases one degree fahrenheit
for As feet descent. At this rate, the
critical point of water would be reach
ed al 4,704 feet, or 61a miles deep.
Where the temperature is that of the
critical point, 773 degrees fahrenheit
water cannot exist as a liquid, no mat
ter how great the pressure. but be-
comes disassociated into its gaseous
elements. The thermometrical gradi
ent becomes more rapid at depths be-
yond these reached by human ohser-
walton, because Of decreased conduC-
tivity in rock Tt may be expected
therefore, that the circulation of water
ceases at 20, 900 feet. But at maximum
depth maximum pressure and temper
allure obtains. 1t must be d horizon Of
solution. Precipitation would hardly
begin till a lowering of temperature
and lessentng of pressure permitted.
Deposition of ore is the direct result
of precipitation, hence actual ore for
nation is limited To II 000 feet