Less than a mile from the Tiptop, in a northwestern direction, is
another property, the Gladstone, locally known as Halberg’s Gold Mine.
It was located several years ago, and after some development was
practically abandoned, but afterwards came into the hands of the present
owners, who have developed the ground quite extensively, built a long
tramway and ore bins, and established a camp.
Nothing was being done at the time of my visit. The mine is something of
a curiosity geologically and mineralogically. The ore body, for there is
only one of any consequence developed, occurs in the gray quartz
porphyry common to the region. A fault has also occurred here,
fracturing the country rock in a manner similar to that in the Tiptop,
excepting that here there is but a single, simple fault. The ore body
consists of a mass of crushed and broken country rock, portions of which
still show distinctly the original porphyritic structure. Generally
speaking, however, the original rock has undergone an extreme
metamorphosis, resulting, in most cases, in more or less complete
mineralogical and physical changes. The porphyry has, by gradual
replacement, been changed to solid ore, or been silicified to a dense
quartzose, sometimes jaspery, rock. Kaolinization of the feldspars has
also taken place. As to the origin of these deposits there seems to be
little reason to doubt that the ore was deposited by percolating waters,
which derived their contents from the neighboring eruptive rocks. These
solutions were carried into the fault plane, and reaching the great
chamber or crushed mass, found conditions of a superior nature for the
precipitation of the minerals they contained. In the pulverized or
finely crushed portions the ore deposition has been most complete,
entirely replacing the original rock, while in the brecciated portions
the ore occurs as incrustations, filling the smaller interstices, but
sometimes penetrating the rock fragments themselves.
The ore body is something over 200 feet in length and 30 feet or more in
width at the Widest part, but thinning out rather irregularly toward the
ends and also downward.
Doubtless it at one time extended some distance upward, but that portion
has been eroded. Along the plane of the fault the line of demarkation
between ore and porphyry is very distinct, as the two bear not the
slightest resemblance, but at the outer edges of the deposit no such
line can be discovered. The mineral gradually disappears, leaving only a
brecciated mass of whitish rock, which graduates into the normal
porphyry. The brecciated condition of the mass is made more plain by the
variety of color assumed by the angular fragments. They are various
shades of green, red, white, and brown, or yellow, caused by copper
carbonates and iron oxides.
Though the original condition of the ore was doubtless sulphide, it now
contains, as the result of oxidation, hematite, limonite, magnetite,
malachite, azurite, chrysocolla, cerussite, wulfenite, chloride of
silver, manganese oxide, and metallic gold. The value of the ore lies
principally in the gold contained, though in one portion of the ore
body, near its eastern end, rich chloride of silver ore is found, with
but little gold. The physical appearance of the ore is no criterion of
its gold contents, as two pieces, with identically the same
characteristics, will differ widely in value. One may contain $2 or $3
in gold, the other several hundred. Should ever a mill be erected in the
district, this ore can be worked to a profit, though this single ore
body will alone scarcely justify the construction of a mill.
On the south side of this fissure or slip is a vein which runs nearly
parallel with the chambered vein above described. This vein can be
traced for several thousand feet. In character the ore is similar to
that found in the Imperial lode. Assays running over $200 in gold have
been obtained from this ore, and $50 assays are not uncommon. The vein
is quite small, ranging from a mere seam to 2 feet. Scarcely any
development has been done on this vein, though it promises better
results than the large “vein chamber.”
The developments on the Gladstone consist of a shaft 60 feet deep. The
first level is cut at a depth of 30 feet from the surface, where drifts
have been run for a distance of 30 feet each way from the shaft, on the
course of the vein, and a crosscut, 28 feet north. East of this, a
15-foot shaft has been sunk in a good sized cut. A large open cut, 100
feet long, has exposed the upper portion of the ore deposit perfectly.
Other superficial work has been done at various points along the vein. A
tramway of 1,700 feet has been constructed from the mine to the bottom
of an adjacent cañon.