The Harrison times., 1901-01-12

OF deep rock decay. And it should
not be forgotten that some of the
most important and best paying
zInc mines in the world have been
mines OF smithsonite. 1t generally
occurs not in hard rock like sphaler-
ite, but in clays or soil where less
expensive labor is required to extract
IT. And there is always a good de-
mand in the market for the carbonate
| ores"
Discussing the bedded deposits, DR.
| Branner says:
/ he beds in which the zinc blende
was deposited have undergone many
changes. The marine sediments
have been lifted out of the water and
made into dry land; they have been
subjected to so much pressure and
twisting that they have been bent
IN some places and in others broken
across and displaced. In some in
stances the beds have been broken
iHto many large angular blocks that
NO longer INT together nicely, but so
| crowd each other as to tip this wav
and that with the edges broken and
crushed against each other. Being
! lifted from beneath the sea the upper
beds have been attacked by streams
that have cut gullies deeper and
deeper into them, and wider and
Wider until some of them are
hundreds of feet in depth and a mile
orsmorc in width. From this briefly
stated history it will be seen why it
IS that through SO large a part of
tffs~--rrlc region of North Arkansas
the ore beds are high in the hills.
They have been left there by the
erosion of streams that have cut
their valleys down through the zinc
beds into the underlying sediments.
The beded ores of North Arkansas
do vary mO.e or less in the thickness
of the ore-bearing portions of the
bed, and in the percentage of spha-
lerite in a given amount of ganguc
But these bedded deposits are
remarkable even in thickness and
richness, and if they change for the
worse in a short distance, they NAV
be depended upon to recover their
richness within an equally short
distance No sudden change in the
thickness or richness of the bedded
ore bodies should excite alarm; it is
only the gradual thinning out or
nprOverishment; of the beds that
should cause uneasincss OF course
a fault may and often does bring the
ore bed up against barren wall,
but beyond the fault the bed can be
rclOca ted-usually with little or no
difhculty-and followed up
The report gives the following
general conclusions regarding the
ores.
The following conclusions seem to be war
ranted
I. The zinc originally deposited in sedi-
mentary beds, mostly of organic origin, in
which much of it is still found.
2 The growth of the crystals in the original
bedded deposits took place prior to the harden
ing of the enclosing salts.
3. The position of the ores has been changed
ted.
+ The changes have been going on ever
since the original deposition and are still in
progress.
5 By means of such changes vertical and
other assures have been filled with ores brought
into them by circulating waters from below
and from all sides
g. The position of the ores in the secondary
deposits has been determined largely by those
structural features that have guided the under
ground waters in their passage through tn c
rocks
l. In some cases the aCCumulations have
taken place along synCIinal troughs; in other
cases in assures along fault lines, and in still
others in the breCci4s formed along ancient
under ground water courses.
s. The subterranean waterways have in
many instances been closed by the deposition
of mineral matter, and the water has been fore
| ed into other channels
g. The Carbonates and siIicates are produced
by the alteration of sulphde ores mostly in
| place,