Dodgeville chronicle. [volume] (Dodgeville, Wis.) 1862-current, 1865-09-28
Written for the Chronicle.
III I " I " G
fCoNTINUED.]

leIclit cidS 80 ViotHANeiJ "oiAN' -
closing of one successful period, and the
opening of another beyond an interval
when the mines were abandoned, because
no longer productive. This peculiar fea-
ture grows doubtless out of the one refer
red to in my last.
The geological history of our world, has
no more distinctly marked eras, than has
the history of every mining region of long
standing. And the folly of supposing that
the mineral resources of a newly opened
country are exhausted, when the veins at
certain depth, or passing through certain
strata, fail to be productive, will appear
when we consider the feature, or study
mining history.
This feature may be studied with interest
IN the history of the Cornish mines, one OF
the Oldest, and most extensive mining re-
gions in the world but will not perhaps
throw as much light on the mining inter
ests of this State, as the history of mines
opened in more modern times. The lead
mines Of England will afford us more in
formation adapted to our interests than
any other, from the fact, that the system
Of mineral veins, and their relation to the
strata more resemble ours. The rock IN
which the veins are found is limestone
The beds like the limestone of this State
are horizontal, or almost SO. The mineral
deposits like ours, somtimes found in crew
ices traversing the strata vertically, at
other times running horizontally between
the beds. An extract or two from reports
made on those lni1es by scientific men,
will convey better idea than I can other
wise give. In Derbyshire, says Prof Bake
well in his iIntroductions to Geology page
304, 'sthe beds Of metalliferous limestone
are separated by bed of basaltic rock,
called toadstone, when vein of lead is
worked through the first limestone down
to the toadstone, it ceases to contain any
ore, and often entirely disappears. On
sinking through the toadstone to TIE sec
ond limestone, the ore is found again, but
is cut off by lower bed of toadstone, I'M
der which it appears again in the third
limestone. In strong veins, particles of
lead occur in the toadstone, but in very
small quantities. In the Geological Oh
server page CHS, we have the following ref
erence to mines in the same strata "Aftcr
some improbable search for lead in shall
low workings between the carbonifcrous
limestone, and its covering Of the arenace-
Gus rocks known as milestone grit, it was
discovered that ore was abundantly dis
tributed in fiat, or streak Of ore between
these rocks, the streak being elongated on
an E. N. E. direction, that Of many Of the
prevailing assures containing lead, in the
adjoining country. By following this fiat
downward on the dip of the beds, many
thousand tons Of very excellent sulphuret
of lead were obtained in a few years. Sub
sequently another mining company sunk
a shaft still further upon the dip of the
beds, and cut the same kind of deposit in
continuation of the same plane between
the milestone grit, and carboniferous lime
| stone From this other streak or fiat of
ore, several thousand tons were also raised
| in few years" "This fiat" says the
writer on the next page, "was composed
of light colored argillaceous matter, from
| Is inches to feet in thickness the met
alliferous portion averaging IA inches thick,
but in some places attaining the full height
of feet, and consisting entirely Of sui
| phuret of lead Several streaks Of ore were
found with the same general direction
The third fiat found working in 1849 was
often surmounted by six or eight inches OF
compact carbonate of lead" The first era
in the Derbyshire miues,-referred to in
the first extract-opcned, and closed in
| the first limestone. During that PERIOD
and it was very long one-the opinion
prevailed generally, that the mineral de-
posts were confined to that part of the
strata, and that deep mining aeould not pay.
Intelligence, and capital however, united
their energies; adopted new system OF
mining, penetrated the toadstone, and
! opened new and successful era in the Sec
ond limestone, beyond an interval Of dark
ness and doubt In the second extract we
see the falacy of the opinion held by many
in this State, that because mineral depos-
| its have been found in the assures of the
upper bed of the strata, and have become
poor, and closed in the lower portion OF
that bed, that they are surface deposits,
and to explore them in depth is waste OF
time and money. The fat referred to in
| the extract is nothing more than what we
should call here an opening, and it rescm-
bles as much as one thing can resemble an
other our pipe clay opening, both in its ma
ture, and relation to the strata. And
there is no reason why that fat or open
ing running between The carboniferous
limestone, and the milestone grit, should
be any mere productive than our pipe
| clay opening running between the blue
| limestone below, and the Galena limestone
above. And yet the opening extends I'M
seen, and unexplored under almost all the
mines in the lead region. 1t is true it has