Grass Valley telegraph., 1858-05-29

II the dlslooation iain the strike,) or
whether 1t is above or below { if il is in the
dip that we should seek for the dislocated
part of the main vein. Zimmerman. gives
a general rule by which this matter can be
determined with mathematical precIsien-
10 introduce it here here would be out of
place, as indeed, 1t would be unreasonable
to imagine It possible that these few pages
should give full instruction in dialling and
! mining engineering. There is no
reason TO suppose that slides or shifts In
veins, or faults in beds, are the results of
sudden movements. Indeed, we have the
best evidence that it is, at least, possible
Tor these changes TO take place gradually
An instance, which is of itself sufficient
proof, is given by Zimmerman, In the work
alseadg alluded TO, page I35. In mine in
the Bflrgstetter Revief, near ClausfhaI at
depth Of five hundred and sixty feet, the
country has shifted on jointure planes,
which were already in existence, in such
manner that the levels, tunnels as we'll
as the marks Of the driller, were disjointed,
to very considerable extent, for more than
a hundred feet.
This interesting occurrence serves also as
proof that slides are not produced by the
younger veins, along whose planes the shifts
occur, but that these slides were the result
/ of causes which had their effect prior to the
! formation of the younger veins. These
veins are themselves enly the substances
filing these crevices. that were themselves
contingent results Of the slideprodueing
action.
Of scientific Interest, not only, but of i'm.
portance too, to the miner are the electric
curreats, which make themselves manifest
in metalliferous veins. with regard to which
some important experiments have been
made By Professor Reich in Freidberg and
by F0r in Cornwall It is but proper in
connection with this, to call attention to a
fact which has been noticed by the inhabi-
tants Of some mining regions in the United
States, at all events, in California as we'll as
in the Southern States, although l am not
aware that it has as yet received the atten-
tion of men Of science allude to the To-
cally well-knewn fact that the electric cur
rents OF the atmosphere evidently exert
their effects more powerfully in tho mmedi.
ate proximity Of vein, than nt points
further removed from it, consequently the
] outcr0ps Of these veins abound in lightning.
struck trees, so that indeed some veins NAV
almost be traced by The trees searred and
lightning blazed Of the effects of electric
! nnPTnnfa fhh
but little Is known as yet. I shall, however,
have occasion to return to this subject
under the head Of gold deposits.
Before closing these Introductory remarks,
it is scarcely out Of place to devote a few
words to what are termed the Indications of
the existence Of valuable minerals in the
lower portions of the veins, as far as these
are established by the appearances at the
surface. Pretenders to q knowledge of ap-
piled geognosy, undoubtedly, seek to let 1t
appear that the surface would under all
circumstances, enable them to prophesv
with certainty, what may be found below
Although this is not TIE case to the extent
to which they would have it believed. vet
experience teaches much which leads to a
correct judgment. Thus, for instance In
the talcose hornstone veins of the talcose
states, which to the uninitiated exhibited
no apparent difference from the barren
sla'es, it is easy for the experienced gold
miner, accustomed to those veins, to dis,
tinguish between the auriferous parts and
those which are valueless. With equal IA,
cility can he separate auriferous gossans
| brown ore from that which contains no
gold. With gold there is, however, less
necessity for endeavoring to discover what
may exist below, than with copper for in
stance, for the former metal is usually
found in greatest abundance In the upper
parts Of the veins, O fact which has been OBJ
served to be the case, almost everywhere,
where gold Ueie mining has been carried on.
The Gold Hill mine in North Carolina, nov
about five hundred feet deep and still as
profitable as ever,) and other mines of the
hornstone veins form probably the only ex.
ceptions. In seeking for gold, the pan is
certainly By far the best gnide. AS regards
copper, the quality and quantity of the COS
san should receive the first attention. This
gosSan termed by the Germans eiserney
Hut by the Spaniards cOIOrddOs,) is the fer!
riferous outcrop of vein, and is ordinarily
hydrated peroxide of iron mixed with sli.
ceous particles, although often other acces-
sorry minerals occur. In Germany this has
for centuries been regarded as a necessary
part of good copper vein. With us these
g0ssanS are almost always auriferous. The
character of the quartz, as regards tho per-
sistency OF the vein in depth. is also mat
ter to which it is Of the UTMOST imp portance
TO attend, lively crystalline variety being
the most preferable-the very reverse, there
fore, OF that which is the case with gold
Lead shows itself, sometimes already i'm
che gossans, in the shape OF ores Of sec