Eureka daily sentinel. [volume] (Eureka, Nev.) 1871-1887, 1884-07-30
PRECIOUS METAL ORE DEPOSITS
Popular Fallacies DisprOved-Th
COmstOck Cited as n Case I'm POfn

Popular Fallacies DisprOved-The
COmstOck Cited n a n ~ i'm Point.
ALDER. Williams, Jr. in the fourth an
nual report of the Directors Of the United
States Geological Survey says:
A very considerable proportion Of Amer
lean precious metal miners Lhave re-
ceived their information directly or indi-
rectly from the California mines; that is,
many miners operating in other portions
of the country have either gained their
practical experience from actual work in
and observstson Of the typical vein mines
OF California, or have become familiar with
the mode of occurrence Of these deposits
by contact with old California miners and
by reading the published accounts Of the
California mines. For o long time the
tendency to g~eneralize irrationally led to
a belief that q northwest and southwest
course was q prime characteristic Of q vslu-
able permanent mines wherever located,
and that the wider the divergence from the
~favorite directions the less the probable
worth of newly discovered veins. A few
noteworthy exceptions had to be admitted,
however-as, for example, the Comstock
lode, which tends nearly north and south
throughout its productive portion. Still
to illustrate the prediction for the north
w~est-southeast strike, the well-known story
may be cited of q celebrated experts hav-
ing reported adversely Upon Q Utah mine,
simply on the ground that its vein ran east
and west, In the face of fair surface expos
ure Of ore, urging that a mine with such q
strike was unreliable. In this case, the
sighted mine subsequently proved to be
a valuable one.
Nature does not bind herself to any such
empirical restrictions. The only approach
to q positive regularity of occurrence that
has been shown by the actual fact 10 that.
as fsulting assures naturally strike with
the general trend Of uplifts, and the latter
are parallel over considerable areas, be-
cause formed by similar and possibly con.
temporary dynamic causes, the veins OF
this class are often found in parallel belts
following the line Of upheaval. So, on the
west flank Of the Sierra, q large number OF
northwest-southwest veins are encoun.
tered; In the Great Basin, where . marked
parallelism of the Basin ranges occurs,
many important north-and-south veins are
met with; while In Idaho, q pr~epondersnce
OF northeast-southwest assures appears.
In each case, the determining cause seems
to be the structural peculiarities OF the
mountain chains. II is not difficult to
understand why q faulting assure should
follow q line approximately parallel with
the trend OF q range; for IL 10 only At
right angles to that direction that there Is
room for q slide or upheaval to take place.
unless, indeed, the main rib be fractured,
9 somewhat violent superstition. There
are other classes of "vein" deposits that
cannot be safely ascribed to faulting, and
these suggest different explanations; yet,
except where mountain sculpture is largely
the result OF erosion, the assures very
commonly have a strike parallel with the
axis of the chain and a dip conforming. to
the original slope Of the mountains,
though diverging more or less from the
surface contour.
Whatever theories are formulated as to
the origin OF mineral veins, it is certain
that an arbitrary strike is not now con-
sidered an essential item In the equipment
Of q successful mine.