Geology Reference
In-Depth Information
Owned by a succession of companies until 1939, the
last was Imperial Gold Mines, Inc., which built a mill
that could handle 140 tons of ore daily. The Sylvanite
vein occurred in rocks of the Applegate Group that
contained high grade ore. With more than 2,500 feet of
underground workings, caving was prevalent. Caving
along with wartime conditions forced closure after
$700,000 in gold was extracted.
A small group of mines southwest of Ashland
are in sedimentary rocks of the Applegate Group, part
of the ophiolite or ocean crust making up the Rattle-
snake Creek subterrane that has been intruded by the
Ashland pluton. Gold here was extracted in placer
operations for only a short time about the turn of the
century. In this district, the Ashland vein, worked for
its lode gold from 1886 to 1939, has been traced for
more than a mile in length and to depths of 1,200 feet.
Underground tunnels at the Ashland mine total 11,000
feet, and $1,500,000 was removed from this vein.
Gold seekers in the Applegate and Takilma
district, which stretches along the southern Oregon
border in Jackson and Josephine counties, began with
placer activity on creeks and rivers in the 1850s.
Operations were numerous, but limited, on bench
gravels along the Little Applegate River, Carberry
Creek, and Squaw Creek, but in the vicinity of Takilma
(Waldo) gold was washed from gravels of Althouse and
Sucker creeks. The largest hydraulic system was at the
Llano de Oro or Esterly Mine northwest of Takilma
that operated until 1945. Gravels here yielded close to
$600,000. Pits, dug into an area of 30 acres on French
Flat, were accessed by hydraulic elevators, and today
these pits, below the water table, are called Esterly
Lakes. At Takilma and Waldo, the rich shallow gravels
of the celebrated Sailor Diggings paid as much as $2.00
per square yard of bedrock, yielding $4 million up to
1933.
Almeda Gold Mine and smelter in Josephine County,
1913 (photo courtesy of Oregon Dept. Geology and
Mineral Industries)
Gold discoveries in the Gold Hill and Jackson-
ville district originally attracted fortune hunters to
southern Oregon in 1851. Several famous placers here
occur in small, and shallow, but rich, concentrations of
gold with few impurities or rock aggregates. The origin
of the near-surface pocket gold deposits isn't well
understood, but the gold occurs in sediments of the
Applegate Group which have been leached by acidic
groundwater. Once a pocket was found and worked
out, the hole was abandoned. South of Jacksonville,
gold at Sterling Creek was extracted by a large hydrau-
lic system that yielded about $3 million by 1914. The
Gold Hill, best known of the small gold pockets, was
found in January, 1857, by a group of mining partners
near the top of the hill now north of town. The miners
discovered the outcropping rock was so full of gold
that they had difficulty breaking it with hammers. The
vein here only went 15 feet but produced $700,000 for
its lucky discoverers.
A number of hydraulic and dredging activities
took place on the Rogue and its tributaries near Gold
Hill. Once the rich placer gold had been worked out,
lode mining began. About 3 miles northeast of Gold
Hill, the Sylvanite Mine on 80 acres started in 1916.
Most copper mined commercially in southern
Oregon has been from the Queen of Bronze Mine near
Takilma in this district. Although discovered as early as
1860, significant amounts of copper weren't marketed
until 1904 when a small smelter was constructed
nearby. Over 25,000 tons of smelted ore was shipped
from the Queen of Bronze and other mines during the
main period of activity from 1903 to 1915. The Queen
of Bronze was the second largest copper producer in
Oregon after the famous Iron Dyke Mine in Baker
County. Large-scale operations ceased in 1933 although
exploration continues intermittently.
Copper deposits in the Queen of Bronze mine
as well as gold from the Takilma district are developed
within the Applegate Group of the Rattlesnake Creek
subterrane within the Western Paleozoic and Triassic
belt. Occurring within an ophiolite sequence, copper
