here - State of Arizona Department of Mines and Mineral Resources

158 PRINCIPAL GOLD-PRODUCING DISTRICTS OF THE UNITED STATES
Tertiary age caps the older rocks (Knopf, 1913,
p. 80-85, and pI. 1).
In the Remini-Tenmile district, two periods of
mineralization are recognizable: one of Late Cretaceous
and one of late Tertiary age (Knopf, 1913,
p. 81). The older and more productive ore bodies
are auriferous silver-lead veins in tourmalinized
and sericitized quartz monzonite in the upper part
of the batholith. The principal ore mineral is galena
accompanied by sphalerite, pyrite, arsenopyrite,
and a little chalcopyrite and tetrahedrite; most of
the lodes are notably tourmaline-bearing. The Tertiary
deposits are low grade and consist of altered
rhyolite impregnated with gold along small fractures
(Knopf, 1913, p. 82). The rhyolite rests unconformably
on the eroded surface of the quartz
monzonite.
SEVENMILE-SCRATCHGRAVEL DISTRICT
The Sevenmile-Scratchgravel district includes the
Scratchgravel Hills which are about 4 miles northwest
of Helena and immediately north of Sevenmile
Creek. The ore deposits include gold placers, rich
silver-lead veins, and gold veins (Pardee and Schrader,1933,p.35-62).
Placer deposits were discovered in Iowa Gulch,
in the northern part of the Scratchgravel Hills,
shortly before gold was discovered in Last Chance
Gulch at Helena in 1864. These deposits were not
large, and there has been little activity on them
since the early days. The amount of gold produced
is not known (Pardee and Schrader, 1933, p. 36).
Other placer deposits along Sevenmile Creek and
its tributaries, including Greenhorn Creek, were
considerably more productive.
These creeks were mined for an aggregate length
of 12 miles or more, and by 1930 yielded an estimated
$1,200,000 (58,055 ounces) worth of gold
(Pardee and Schrader, 1933, p. 59). From 1930
through 1959 the yield probably was less than 750
ounces (Lyden, 1948, p. 58-59).
The lode deposits were discovered before 1872.
Some rich silver-lead ore was mined in the early
years, and in 1914 rich gold ore was found in the
Franklin and Scratchgravel mines. The period
1916-18 was one of great prosperity in which the
lode mines, primarily the Franklin and Scratchgravel
mines, produced at least $550,000 (26,600
ounces) in gold. By 1919, however, costs of supplies
and labor forced these mines to close, and lode
production was then limited to desultory output of
several smaller mines. Total lode gold production
of the district through 1959 was about 48.700
ounces; total lode and placer production through
1959 was at least 108,000 ounces.
The country rock consists of shale, sandstone, and
limestone of the Belt Series of late Precambrian
age and quartzite. shale. and limestone of Cambrian,
Devonian, and Mississippian age. The bedd('q rocks
are folded and are intruded by diorite anc' quartz
monzonite, probably offshoots of the Boulde- batholith,
of Cretaceous or Tertiary age (Parnee and
Schrader, 1933, p. 36-37; 59).
The ore deposits in the Scratchgravel Pills include
contact-metamorphic deposits, gold veins, and
lead-silver veins. Most of the gold deposits E,re goldquartz
veins in quartz monzonite. Pyrite is the most
common ore mineral in the unoxidized ores., and in
some veins there are scattered grains and bunches
of galena and a little sphalerite. Gold can be panned
from the oxidized ore (Pardee and SchradElr, 1933,
p.37-58).
In the Sevenmile Creek area the lodes yielded
chiefly silver, lead, copper, and gold. The lodes are
irregular pockets or pipelike bodies in limestone
near the quartz monzonite contact. Most of the ore
was oxidized and the chief constituents were iron
oxides, gold, silver-bearing galena, and copper carbonates.
STEMPLE-VIRGINIA CREEK DISTRICT
Located about 28 to 35 miles northwest of Helena
in the drainage basin of Virginia Creek, the Stemple
(Gould) -Virginia Creek district contained both
placer and lode ore deposits. The lode ore was valued
chiefly for gold; only about 5 percert of its
value was silver (Lyden, 1948, p. 63). Mining began
at least as early as 1878 when the HC"llestake
lode in the Stemple area was located; in 1884 the
Jay GOUld, the principal mine in the district. was
discovered (Pardee and Schrader, 1933, p. 77, 86).
These and other mines in the district were worked
intermittently. Beginning in 1922 the Jav Gould
mine operated almost continuously to 1942 when
all minework was suspended. A small pr'lduction
from the district was reported for the period
1943-51.
The gravels along Virginia Creek have been
mined from Stemple to its mouth, a dis";ance of
about 8 miles. Their date of discovery has not been
ascertained. The gravels were moderately rich but
not very deep; prior to 1927 they yielded at least
$600,000 (29,028 ounces) in gold (Pariee and
Schrader, 1933, p. 86). From 1927 to 19·i2 small
intermittent production was reported (Lyden, 1948,
p. 63), but it probably totaled less than 200 ounces.