Gold Districts of California
Location. Alleghany is in southwestern Sierra County. This district is in a belt
of gold mineralization that extends from Goodyear's Bar, south and southeast through
Forest, Alleghany, Chip's Flat, and Minnesota. This gold-bearing belt continues south to
the Washington district in Nevada County. The Downieville and American Hill districts are
to the east, and the Pike district is to the west.
History. The streams in the area
were placer-mined soon after the beginning of the gold rush, and the Forest diggings were
discovered in the summer of 1852 by some sailors. Some of these sailors were
"Kanakas" or Hawaiians who also had deserted their ships in San Francisco.
Forest, first known as Brownsville and then Elizaville, got its present name in 1853. The
Bald Mountain and other drift mines were highly productive from then until around 1885.
Hydraulic mining was done at Minnesota and Chip's Flat during these years. The town of
Alleghany was named for Alleghany, Pennsylvania.
Quartz mining was reported to have begun in the district in 1853 at the German Bar and
Irelan mines. Although the quartz mines were moderately productive until the 1870s, drift
mining was the principal source of gold then. The rediscovery of the Tightner vein in 1904
by H. F. Johnson (erroneously given as 1907 in many reports) led to the revival of lode
mining, which continued until 1965.
Alleghany was the only town in California after World War II where gold mining was the
principal segment of the economy. After 1960, production from the district, which had been
averaging more than $500,000 per year, decreased greatly as more and more mining
operations were curtailed. By 1963, the output was less than $100,000 per year. The
Sixteen-to-One mine, the largest gold source in the district, curtailed normal operations
late in 1962, and the Brush Creek mine, the second largest operation, was shut down in
1964. At the end of 1965 the Sixteen-to-One mine was completely shut down, ending an
operation that had lasted more than 60 years. (Editor's note: the Sixteen-to-One mine is
again in operation as of 1998.) Intermittent operations have continued at several mines,
such as the Kate Hardy, Oriental, El Dorado-Plumbago, and Mugwump mines. Several of the
mines received Federal exploration loans. Skin divers are active in the streams of the
Alleghany was the most famous high-grade gold mining district in California. The value
of the total output is unknown, estimated at $50 million. Much of this production was from
small but spectacularly rich ore bodies.
Geology. The district is underlain by north and northwest-trending beds of
metamorphic rocks of the Calaveras Formation (Carboniferous to Permian), serpentine, and
greenstone. In the vicinity of Alleghany and Forest this formation has been divided into
six units: Blue Canyon Slate, Tightner Formation (chiefly amphibolite and chlorite
schist), Kanka Formation (conglomerate, chert, and slate), Relief Quartzite, Cape Horn
Slate, and the Delhi Formation (phyllite and slate). These rocks have been invaded by many
basic and ultra-basic intrusions; the ultra-basic rocks have been largely serpentinized.
Mariposite-bearing rock, locally known as "bluejay," is commonly adjacent to the
serpentine. Also present are fine to medium-grained dioritic dikes. The higher ridges are
capped by andesite and basalt, which in places overlies auriferous Tertiary channel
Ore deposits. The gold-quartz veins strike in a northerly direction, dip either
east or west, and usually range from two to five feet in thickness. They occupy minor
reverse faults, and occur in all of the rocks of the Calaveras Formation, and in the
greenstone. The largest number of mines are in amphibolites of the Tightner Formation. The
most characteristic features of the ore deposits are the extreme richness, erratic
distribution and small size of the ore shoots. Th range from small masses of gold and
quartz yielding a few hundred dollars to ore bodies that have yielded hundreds of
thousands of dollars. One ore body at the Sixteen-to-One mine, which had a pitch length of
40 feet, contained nearly $1 million, while another at the Oriental mine about 14 feet
long yielded $734,000.
The gold occurs in the native state commonly with arsenopyrite but only small amounts
of other sulfides. In a few places pyrite is abundant. The numerous serpentine bodies and
associated mariposite rock are structurally important in the localization of the ore
bodies. The quartz veins tend to fray or bend near serpentine, and it is in these frayed
or bend portions of the veins that the high-grade ore bodies are often found. High-grade
ore also is found in vein junctions or in sheared portions of the veins.
Channel gravels. A major tributary of the Tertiary Yuba River extended south
from Rock Creek through Forest and Alleghany and then southeast through Chip's Flat and
Minnesota to Moore's Flat in Nevada County. This is commonly known as the "Great Blue
Lead" or Forest channel. It was uniformly rich except where cut by later channels.
The largest gold producers were the Ruby, Live Yankee, and Bald Mountain drift mines,
where many coarse nuggets were recovered. During the late 1930s a number of fist-sized
gold nuggets were recovered from the Ruby mine. These were displayed for many years in the
Sierra County exhibit at the California State Fair in Sacramento.
Mines. Lode: Brush Creek $4 million+, Dreadnaught $50,000 to $100,000, Docile
$100,000 to $200,000, Eclipse $20,000 to $50,000, El Dorado $325,000, German Bar $200,000,
Gold Canyon $750,000 to $1 million, Gold Crown, Golden King $250,000, Irelan $350,000 to
$500,000, Kate Hardy $700,000, Kenton $1 million to $1.25 million, Mariposa $50,000,
Morning Glory $80,000 to $100,000, Mugwump (both lode and placer) $50,000, North Fork
(both lode and placer) $125,000, Oriflamme, Ophir, Oriental $2.85 million, Osceola,
Plumbago $3.5 million, Rainbow $2.5 million, Rainbow Extension, Red Ledge, Red
StarOsceola- $200,000, Rising Sun $58,000, Shannon, Sixteen-to-One $25 million+, South
Fork (both lode and placer), Spoohn, Tightner, Twenty One, Wyoming, Yellowjacket. Drift:
Bald Mountain $3.1 million, Bald Mountain Extension $500,000 to $1 million, Gold Star
$250,000+, Highland & Masonic $300,000+, Live Yankee $750,000 to $1 million, Ruby $1
Excerpt from: Gold Districts of California, by: W.B. Clark, California
Department of Conservation, Division of Mines and Geology, Bulletin 193, 1970.
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