The times. [volume] (Richmond, Va.) 1890-1903, 1893-11-19
DEPOSITS OF GOLD.
rHHxx ORIGIN IN FISsUREs AND
PLACEEs.
uov ,hs Southern salphuret Ores may De
worked Probably and Con
finuously.


for small quantities Of gold have been de
,ec,ea IN sea-water: but, again, donbties'
the sea received IT from the rocks.
There has envidently been an increasing
concentration and availability OF gold an'
o,ner metals. In the strata the quantity
e. 40 small as 20 be undetectable; IL u
thence carried and concentrated in veinl
in n more available form; II is next SCI
free along the backs OF these veins IN
stu more available form; II Is last cartie'
down by currents along with other maze
rails. neatly sorted ard deposnied IA
plaeers in u form the most aVahapie "
all" ..
Mineral veins are especially sbundan'
in mountain regions, and IL Will ne ~
resting to know how they derived tie''
contents from the sea.
Origin Of Mountains.
Professor lie Conte says that mountains
are made cut of lines Of thick sediments
once marginal sea bottoms. or nnes - -
mick o0-shore deposits, constituting n
mass Of enormously thick strata cfushea
,ncetber Iaterally and sWelled up along
tte line Of crushing.
Tbe strong foldings OF mountain strata
Inevitably produce fractures. ana "h'h
these assures are filed at the lirne OF
formation by igneous injections they are
called dikes: but II. subsequently, WIN
mineral matter by n different pFoceNS,
they are fissure-veins. The coatehts OF
mineral veins seem To have been deposit
ed from hot alkaline solutions coming Up
through assures; in other words, from Not
alkaline springs
Meteoric waters, circulating in the int
In
ward. upward, or laterally- slight
Iv soluble matters in their course, in
cracks. cavities or great assures. forming
fossil casts geodes, amygdules, nlltIa-
tion-veins and fissure-veins. AS 10 d.
rection. the up-coming waters, especially
in metamorphic and volcanic regions, de-
post most freely, and are most metaliifer-
Gus. because they are hot and often aka
line. and. therefore, most powerful SOL
vents. and, Of course, cool gradually on
approaching the surface. But that down
ward percolatiug waters may also deposit
metallic ores Is proved by the fact that
these are sometimes found depending, like
stalactites. from the roof of cavities. AS
TO the different kinds Of veins, those OF
great assures are the most prolific, be-
cause these assures are the highways OF
water from the heated depths. But every
kind of waterway viii receive deposits;
and as the kinds Of these are Infinitely
various and pass by insensible gradations
into each other. so also Will be the VEINS
which FIJI them. The open fissuTe IS the
easiest and therefore, the most travelled
highway In these, therefore, We have
the most perfect type of veins, with their
bounded structure and their selvages,
their great size and continuity"
True Fissure Veins Intersect.
Fissures are usually in systems parallel
among themselves and to the axes OF
mountain chains Parallel veins are apt
10 have similar metallic contents, while
veins running In different directions (un-
less sometimes at right angles are apt
TO contain different metallic contents. The
reason OF this is, that parallel assures
belong to the same system-were formed
at the same time, broke through the same
strata, and were filed under similar con-
ditions. and, therefore. with the same
materials; while assures running in differ-
ent directions were probably formed at
different times. broke through different
strata, and were filled under different
conditions. Veins usually interSect the
strata; but in some cases where the stra-
Ia plains are highly inclined the opening
is between these planes and the veins are
therefore, conformable with them
called true fssure-veins. and those which
conform TO the strata bedded veins. but
there is often 10 other difference between
them
Different Kinds OF Veins.
j. Arthur Phillips in his Treatise on
ore Deposits divides metailiferous de-
posits into three groups. Superficial"
"Strathed" Unstratihed." ard sub-di-
yides the latter into eight different class
es. three OF which he calls regular and the
others irregular. The regular unstratihed
deposits are aggregations Of mineral, diff
fering IN character from the enclosing
rocks. In assures formed in these rocks
subsequently 10 their consolidation, which
he calls true veins, segregated veins, and
CAST veins.
A true vein or lode he defines "as a
assure Of indefinite length and depth, fill
ed with mineral substances, and often
containing metalliferous ores, traVersing
the enclosing kffndependentsy oftthelr
structure. 9nd which is not Parallel TO
their foliation or qualification"
Segregated veins, he says differ from
true veins inasmuch as they are conform
able with the bedding or foliauon OF the
country (enclosing) rock"
Cast veins, he says, are metalliferous
deposits which occur I'm limestone rocks
only, and being confined TO a single stra-
tum or formation are necessarily limited
In extent
or the segregated veins he says further.
1T Was formerly believed that veins of
this description are less persistent than
true lodes. that they are richer nearer
the surface than elsewhere, and that they
frequently terminate by pinching out both
I'm depth and in horizontal extension. Re-
cent mining operations have however.
materially modified the received viens re-
specting the value and persistency Of the
so-called segI egated veins. Many of them
are OF great thickness ana extent. and
after having been worked to very con-
siderable depths. have been there found
as productive as they were nearer tn,
surface. The character of the vein-stone
OF such deposits frequently appears 10
IN no way vary from that OF true assure
veins. from which they often differ in no
respect except that their course is paral-
lei 10 the strata between which they lie"
Besides extending uninterruptedly for
considerable distances, deposits Of this
class sometimes form femticular masses Of
limited extent; these are, however. often
followed by others of a similar description
forming a series resembling a moro or
less interrupted lode. The quartz veins
so numerous i'm Canada. New England
and In the Allegheny Mountains are gem
orally examples Of deposits OF this class.
as are, for the most part, the aurlferous
veins OF California. - The ore-bearing
mass does not always crop out at the sur
face. One OF the most important
constituents OF segregated veins is gold,
with which either pyrites. blende. galena
or chalcopyrite is almost always to some
extent associated"
In the report OF the Geological Survey
OF North California q. h. Hanna saws