The Salt Lake herald. [volume] (Salt Lake City [Utah]) 1870-1909, 1907-05-20
Rutte's chaIcoeite Deposits.

In a recent suggestive contribution to
/ this journal, James f. Kemp of Columbia
/ university touched upon this matter in his
usual informing way. Referring to the
secondary enrichment namely the chai-
coclte ore bodies of Butte, the professor
quoted the suggestion that these deposits
are due to uprising solutions of copper,
| set in motion by thermal activity asso-
| ciated with the late intrusion of rhyolite.
! 1t appears likely that the deposition of
/ copper Is the last notable act of the as
cendlng solutions, rather than one of the
! results OF descending surface waters. The
] occurrence of copper below zones rich in
other metals, and far too deep for the
penetration OF the grOund-waIer, JustifieS
! restricted application of former theories.
/ At Butte, despite the shattered condition
/ Of the country, consequent upon three or
four successive periods of fractUring the
/ chalcoCite has been found from LOCO to
/ ECO feet below the possible bottom of the
! ground-Water, so that it Is wholly I'M
likely that solutions enriched at the OK
pense of the upper parts of the lodes
could have been responsible for the ore
bodies of the deep levels.
Bingham Conditions Cited.
Moreover, at Mt Morgan, in Queens
land, and at Bingham, lin Utah, copper
sulphldeS have been found in notable
quantity underneath bodies OF ore rich in
/ other metals, but barren of copper when
/ exploited near the Surfacetan for several
! hundred feet below it. In these cases it
/ is not at the base of the oXidized zone
( or near the bottom of the grOund-water
/ that the copper has been found, but at
/ depth apparently beyond the reach of
| superficial agencies and within the do
/ main of the uprising solutions, to which,
at another time and under different con-
| ditions, the ore deposits owe their pri-
mary origin We are thoroughly of the
/ opinion that Professor Van HiSe and
other authorities have paid too little at
/ tentiOn to the comparative ShallOwneSS of
/ the ground-water, which does not extend
/ indefinitely downward from its well rec
ogniZed upper level but is really a thin
| blanket of water. 500 or 400 feet thick. 1t
/ is artificially depressed by mining opera
/ tons. and it is tapped by the lateral
workings in the upper portion of a mine
/ so as to drain into the shaft Miners
| know what it means to take up the
/ water at the 700 S00-foot level, and
they know that by the use of dams and
pumps they can keep the bottom of their
mine dry That is because they are be-
/ low the zone of ground-water.
Cobalt's Economic Geology.
! At Cobalt there is practical interest in
/ this problem of economic geology, and we
I hope that the engineers in charge of OPP
/ er2tiOns Will collect some useful facts. In
/ regard to Mi HiXon'S reference to car
/ bOnaceous matter as a precipitant, this
| is subject that the present writer
| studied with keen interest several years
I ago, notably at Rico, in Colorado; there
( the gold and silver veins are rich only
/ while traversing shale, limestone and
/ sandstone where these rocks are black
/ ened by carbOnaceOus matter. However
| attractive the theory, it must be applied
/ with hesitation, for of this we are sure,
namely, that while the solvents for gold
are few and sparingly distributed, the
precipitants are many and everywhere
obtainable In the case of silver. the
solvents are more numerous, and the So
| luton of the sulphide by surface waters
is chemically reasonable, but even in this
case a precipitant seems to Turk at every
turn. and we need not lay stress on any
particular one.
| We agree with Mr.. Hixon, however,
that the association OF gold and silver
| with carbonaceOus matter is a coincidence
too frequent not to have a relation. In
some cases the carbon may be access
sorry after the fact, as indicative of by
drocarbon gases. or it may have been in
directly responsible by precipitating iron
| sulphide from sulphate waters, the iron
| sulphide becoming the immediate agent
/ in the precipitation of the precious metals.
1t is a fascinating subject, and we hone
that some of our mining biologists will
1 give their testimony, to the end that all
| Of lie NAV learn something more.