Grass Valley telegraph., 1858-05-29

riOr of our planSSS8gaght to the surface by
mineral waters orM6YNeam, end chiefly oc-
cupying the creviSgS>Nhemselves, whilst the
surplus only, which couM NOT fnd place
in these, distributed Itself among the sur
face waters, whence itNwas afterwards pre-
cipitated"
This theory also explains the source whence
metalliferous deposits like that of copper in
the MansfeIdt states, ,were derived. It is
likewise in accordance Whilst that Professor
Gotta SO ably explains the phenomenon of
paralleliSm and corIceRtrie repetition of the
vein minerals, which is frequently to be seen
in, such great perfection. He supposes these
to have been in one and the same solution,
or in a solution periodically replenished
from the same. or from yaRious sources, end
that the minerals were preoiprseted in sue
cession on the two walls fn< <theorder of their
selubility, those being frstN thrown down
which required the greatest amount of heat
and pressure to render MSm soluble.
The theory advanced BY me, in which the
object was to explain the Successive appear
ances of gold, lead andeopper, SO frequently
noticed in peculiaE>class Of our Southern
auriferous veins, an1of which more shall be
said hereafter, is -ikewise based upon this
opinion regarding the sSffgin6f veins.
1t is very evident to all who have paid
any attention to veins, that those causes
which produced the, 1lling up of the vein
creVises, have even at odA DAY not ceased to
exist that changes, such as decomposition,
solution, and reprecipitRGon, are constantly
going on bu. it is equally plain that, for
the production Of ths<gEander effects, various
other important assistant circumstances
must have existed, which are now to be de-
tected in their resulfssNSnly.
The high temperature, ,raGd likewise high
pressure, which must have.attended On ear
lier state Of the developments of our globe,
can alone explain effects for whose cause we
would seek in vain among existing laws, IN
accompanied by cireqmstances which gave
them greater force.
To :he miner it may be of less Importance
to know that the materials he seeks were
derived from certain source, than it is to
be aware that veins >are really but filled
crevicos, and that, consequently, those SUBJ
stances, which constitute the veins, must
have taken possession of their present posi-
tion at later Period than that in which
the rocks, through which they pass, we're
formed. AL veins are younger than the
evur-t1y J, Uuu tvd0v IL, wIJuout any reason,
that many writer's regard those only as true
veins which dip on strike unconformably
with the country rocks, for it is evidently
quite immaterial what peculiar relative po-
aition is occupied by the two, as far as con-
Germs the origin Or The general character of
the veins. CreVices may be formed in any
direction, and it is but reasonable, indeed,
to suppose that 9e planes Of stratifoation,
being possessed of less eGeaion, will at least
as readily present themselves for the forma
tion of cracks or Gassures, as those planes
which travers th@> >moFe&compact and less
fragile portions o: tGe<ocks& These are the
bed veins of the Germans Another class
comprises the veins of lsnticular character,
which fill the interstiees>at the semi-crystal-
line, rhomboidal j9i9ture planesof the tai
cose states they will be more fully treated
under the head osp,the {" Iornstoue Gold
Veins" Still another division is that of the
contact veins" 1t emb8Aes those which are
found at the contact sffa3aof dixie of some
igneous rock, and tSkeountry rock through
which it passes. 70, ,the~miner they are par
ticularly important, as@thoy are almost uni
versally providefwith useful minerals, and
as their persistoncy E@Gorkablo depths can
be relied upon withi gres4er certainty than
with other veins, sHs$eauses which may in
duce other veins to giT& out, in many in
stances, do not Szist in these
From what has S6sen already said, it is
evident that by far<the majofty of veins are
tabular or we&ge-like masses, with a far
more extensiveN7ongikMinal than lateral
diameter. Irregularities occur as a matter
of course. CrevieeA cannot be expected to
follow perfectly &Sne lines; and, besides,
very frequently asssE' ne qrevice was formed,
but before it wasr filed, one or, the other
side, or both, were pressed upwards or down
wards, forwards or Backwards, and we find
that the vein swellG out Or narrowa beyond
or below its usual dimensions. De la Beche
has illustrated this avery. simple draw
ing, which shows lthatS,tese Irregularities
were only caused BS~+hQse parts of the WALL
ing which originally ftted into others, being
pushed past one another, In whatever direc-
tion it may be. ~
The lenticular veirs> are enothing more
than these very strongly developed; with
them the narrow portions have SO completely
contracted, that often no detlareation exists
by which to trace oOn9ectiOn from one to
the other, and in some cases they are SO far
removed from one anotiNr, that connection
is apparently difficult even to imagine.
1t is of the utmost Importance in mining,
to know when slide oceqss> on which side