Weekly Arizona journal-miner. [volume] (Prescott, Ariz.) 1903-1908, 1906-03-28
ORIGIN AND NATURE
OF FISSURE VEINS

though this process is known to affect
other classes Of veins as well.
There is much difference Of opinion
among miners as to the direction of
/ flow Of underground waters. Some be.
/ licvc these waters are forced into the
i workings from below, others think they
came from above; but 1t ~ fairly safe
to assume that in most instances the
ascending waters are hot, and that
where the water is cold IL has no direct
connection with the sources Of heat
found in great depth. Much depends
on local conditions. The waters in the
deepest mines in California, nearly
1900 feet vertical, are not over 80
degrees Fahrenheit, while in the Com.
stock lode, Nevada, water having TEN.
peraturcs varying from 100 to 15s de.
grees Fahrenheit are found far above
the 5000 lcvel-betwecn 1000 and
1000 feet from the surface, as well as
deeper The surface waters Of the
Comstock lode are cold. At Steam
boat Springs. Nevada, the attempts to
mine have been futile because the
scaiding waters and steam issue Mt
the surface. In Colusa county, Cal,
n quicksilver mine having what would
bc good, payable ore under ordinary
conditions cannot be worked owing TO
the intense heat Of the mine workings,
and the existence of scalding waters at
numerous places in the mine. In time,
doubtless, both this and Steamboat
Springs and similar places will be-
come cold and then the miner Of the
distant future may find profitable
employment in the exploitation Of the
mineral deposits existing in these
and like veins elsewhere.
In shaft sinking water often
comes into the workings from below
with considerable force, occasionally
in such abundance ms to temporarily
drive the miners from the shaft, wher
only by vigorous and long-continued
pumping can the water be controlled
Later this food is overcome and thu
sinking proceeds AS before; the
"spring" is passed and sometimes
completely drained, and comparative
" little water is encountered, when
without warning, another gushing
spring is encountered, and the sam
process Of pumping must again b.
1 gone through. This proves conclu
!. sivcly that the water Is due TO down
ward flow, and Is the result Of tappini
n fssure, seam, or crcvicc which ha'
communicated with a water.saturate'
n zone.
q The downward flow Of surface waite
n usually changes the physical appear
y ance of the vein to great extent. Ok
4 idcs and carbonates abound where orr
q ginally sulphidcs and silica, the chang
- from the oxidized zone TO the sulphid
g being sometimes gradual but ofte
4. abrupt.
Veins are also altered greatly b
~ movement Of the walls and pressuT
n which took place long after the vel
z was formed. Solid masses OF ore ar
y crushed to the condition Of sand, q
d broken into millions of fragment
e large and small, these being general
'c re-cemented by silica or calcium ca
'e donate, or both, again forming soil
m vein, but the evidence Of brccciatio
IL may generally he plainly seen Some
ID times gouge forms on one wall, o.
,r casionally on both. At one time II wa
r. thought that whore the gouge occurre
10 on the foot wall only IL was due TO fir
" particles Of suspended clay, and oths
n mineral matter settling by gravity O
III the lower or footwall, from the sol'
~ tions which filed the fssurc. Tn
ly theory contemplated an open crevic
st and there may be examples Of its o
X currcncc, hut ordinarily clay selvag
n gouge. etc, at the side Of vein
he due wholly TO movement Of the wall
is This selvagc may be hut fraction I
n. an inch or IL may he many feet. On Il
In Mother Lode of California gougc o
ry ten occurs UP to 40 feet in width us
\. ally mass ~ crushed, foliated. In
n. trous black slate, sof, and easily mi
= ed, but extremely dangerous swcllir
and crushing timbcrs, and filing q
II excavations completely II not proper
held. often these great gouges co
\ tain rounded masses 81 quartz, som
iimna WEIGHING a ton or moro. hnt us