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This CD contains the page images and searchable text from a 1932 United States Geological Survey report on the gold-bearing formations of the Alleghany district, in the southern part of Sierra County, California. The district is known for the high-grade gold ore of its quartz veins, which between the 1850s and 1930 yielded $20 million, and now-rare lode mining continues there today.
USGS Professional Paper 172 expanded upon the Colfax and Downieville folios of the Geologic Atlas of the United States, published 30 years earlier. The report updated the descriptions, made by Waldemar Lindgren in the Colfax folio, of three quartz formations, and it identified two additional gold-bearing formations. After a general discussion of area geology, the report details and maps mineralogy, origin of deposits, and the key lode mines and prospects of areas draining to Oregon Creek, Kanaka Creek, and the Middle Fork Yuba River. Graphics include photographs of quartz and mineral samples, colorful general and local geologic and topographic maps and sections, and intricate drawings of the tunnel networks of the largest mines.
Contents:
Outline of the report
Part 1. Geology
Introduction
Scope of the report
Location and topography
Field work and acknowledgments
Previous work Rock formations
“Bedrock series”
Blue Canyon formation
Tightner formation
Kanaka formation
Areal extent
Conglomerate member
Lower slate and greenstone member
Chert member
Upper slate and greenstone member
Sections
Relief quartzite
Cape Horn slate
Serpentine
Gabbro and diorite
Quartz diorite
Granite and aplite
Age of the “Bedrock series”
“Superjacent series”
Early gravel
Intervolcanic gravel
Andesitic breccia
Basalt
Pleistocene and Recent gravel Geologic structure and history
Structure of the “Bedrock series”
Faulting
Tertiary history
Development of the present topography
Part 2. Ore deposits
History and production
The veins
Scope of descriptions
Distribution
Relation to country rock
Size and structure
Mineralogy
Summary
Chlorite stage
Quartz stage
Arsenopyrite and pyrite
Quartz
General features
Vacuoles
Plagioclase
Barite
Chalcedony
Carbonate and sericite
Apatite
Beidellite
Carbonate stage
Character of mineralization
Carbonate
Mica (mariposite and sericite)
Chlorite
Talc
Carbon (graphite)
Palygorskite
Rutile
Quartz, chalcedony, and opal
Sulphides
Gold
Final stage
Oxidation
Oreshoots
Character
Productivity of veins of different types
Favorable structural features
Mineralogic indications
Probable persistence in depth
Origin of the deposits
Age of the veins
Depth of vein formation
Origin of the fissure systems
Pressure and temperature
Source of the minerals
Possibility of derivation from the wall rock
Minerals of the chlorite stage
Quartz and carbonate
Arsenopyrite
Mariposite
Chromite
Gold
Graphite
Plagioclase
Barite
Method of vein formation
Chlorite stage
Quartz stage
Possible recrystallization
Replacement
Fissure filling
Conclusions
Carbonate stage
Summary
Mine descriptions
Mines of Oregon Creek drainage basin
Brush Creek mine
Finan prospect
Kate Hardy mine
Hardy Kate prospect
Tomboy prospect
Eureka mine
Oak prospect
Mugwump mine
Gold Bug prospect
Federal mine
South Fork mine
Amethyst mine
Diadem mine
North Fork mine
Mines of Kanaka Creek drainage basin
Kenton mine
Roye-Sum prospect
Oriental mine
Frances D prospect
Spoohn mine
General Sherman prospect
Wyoming group (Dead River)
Wonder prospect
Rainbow mine
Rainbow Extension mine
Sixteen to One mine
Ophir mine
Eclipse mine
Morning Glory mine
Extension of the Minnie D mine
Minnie D and Lucky Larry mines
Osceola mine
Panama prospect
Red Star mine
Rao prospect
Mayflower prospect
Mariposa mine
Central mine
Snowdrift prospect
Eldorado mine
Yellow Jacket (Colorado) mine
Eastern Cross group
Rising Sun mine
Iroquois prospect
Dreadnaught mine
Belmont prospect
Golden King mine
Docile mine
Continental mine
Mammoth Springs mine
Kinselbach (Acme) mine
Mines in the drainage basin of the Middle Fork of the Yuba River
Mountain View prospect
Maryland prospect
Oriflamme mine
Irelan mine
Arcade mine
Cooper prospect
Plumbago mine
German Bar mine
Gold Canyon mine
Independence mine
Future of the district
Plates
Geologic map of the Alleghany district, California
Crumpled hornblende schist of Tightner formation between Morning Glory and Osceola mines
Slate of the Blue Canyon formation, near Mammoth Springs mine
Crumpled hornblende schist, siliceous facies of Tightner formation, valley of Kanaka Creek
View from Alleghany, looking down valley of Kanaka Creek
Geologic Map of the region surrounding the Alleghany district
Hornblende schist with streaks of quartz, Tightner formation, near lower Osceola tunnel
Basal conglomerate (tillite?) of Kanaka formation near transformer house, Alleghany
Chert of Kanaka formation, South Fork of Yuba River near Washington
Detail showing contorted banding in chert, South Fork of Yuba River near Washington
Relief quartzite, fold in quartzitic slate, Kanaka Creek near Rapps Ravine
Typical exposure of serpentine, nearly bare of vegetation, valley of Kanaka Creek
Eocene gravel at old hydraulic workings south of Alleghany
Flows of Pleistocene basalt capping Miocene andesitic breccia, Bald Mountain
Map showing location of fault east of Alleghany with reference to the Mother Lode system
North side of valley of Kanaka Creek looking toward Sixteen to One mill, showing shoulder below lava
Outcrop of vein on footwall side of Sixteen to One vein
Junction of Sixteen to One vein and vein along steep fault
Principal fissures of the Alleghany district, projected to plane of 3,700-foot contour
Map of the Alleghany district, showing principal mine workings and mining claims
Structure sections through the eastern part of the Alleghany district In pocket.
Vein with septa of altered country rock separating quartz strands, North Fork mine
Junction of main vein and fault vein, Sixteen to One mine
Altered but unsheared country rock separating quartz strands, Rainbow mine
Banding in vein due to shearing, Sixteen to One mine
Quartz stringers in footwall of vein, Eldorado mine
“Crossover” stringers between hanging wall and footwall, Kate hardy mine
Vein with sharp footwall due to faulting and frozen hanging wall with quartz stringers, Plumbago mine
Quartz stringers in altered slate close to main vein, Rainbow mine
Lenses of quartz in crushed slate along wall of Clinton veils, Rainbow mine
Lenses of quartz and carbonate in crushed slate, Kate Hardy mine
Quartz stringers cutting Cape Horn slate, Brush Creek mine
Breccia containing quartz fragments, cemented by fine-grained quartz, along hanging wall of vein, Eldorado mine
“Headcheese” breccia, Eldorado mine
Vein with well-marked “walls,” Plumbago mine
Walls of vein due to postmineral movement, Plumbago mine
Footwall of vein marked by curving fault, Plumbago mine
Fault plane passing from footwall to hanging wall of vein, Sixteen to One mine
Quartz displaced by minor fault, Eldorado mine
Wedge of quartz bounded by faults, Oriental mine
Specimen of ribbon quartz, German Bar mine
Ribbon quartz with bands parallel to walls, Sixteen to One mine
Ribbon quartz cut by transverse sheeting, Kate Hardy mine
A, Junction of Oriental and Alta veins, Oriental mine
Vein with lower strand showing crinkly banding and strand above containing wall-rock inclusions, Eldorado mine
Development of chlorite and albite in saussuritized gabbro
Grain of chromite in serpentine veined by antigorite
Vein quartz showing inclusions associated with septa of country rock
Vein quartz with abundant inclusions
Arsenopyrite veined by quartz and crystalline against quartz, with gold replacing arsenopyrite
Arsenopyrite broken and veined by quartz, with gold for the most part replacing quartz
Pyrite veined by quartz
Pyrite veined by quartz which shows clear border
Quartz grain showing crystal faces surrounded by quartz with allotriomorphic texture
Quartz crystal with core containing abundant vacuoles, surrounded by growth of relatively clear quartz
Same as D, with crossed nicols
Vein quartz showing rosette of outward-pointing quartz crystals
Quartz crystals normal to face of arsenopyrite crystal
Quartz crystals elongate normal to wall of vein
Quartz veinlet with cross-fiber structure
Samite as B, with crossed nicols
Vein quartz showing strain twinning and microbrecciation
Quartz crystal showing vacuoles in zones parallel to prism with grain boundary due to later fracture
Same as E, with crossed nicols
Cloudy quartz cleared in zone of microbrecciation
Same as A, with crossed nicols
Change in grain close to wall of vein, probably due to later fracturing
Same as C, with crossed nicols
Albite, dark from abundance of vacuole inclusions, intergrown with quartz
Same as A, with crossed nicols
Detail of A, showing contact of quartz and feldspar
Albite with zoning due to vacuoles
Intergrown quartz and albite showing vacuole inclusions
Vacuoles with gas bubbles in quartz
Inclusions in quartz—clusters of minute inclusions and negative crystals with bubbles
Quartz crystal showing zonal structure due to arrangement of vacuoles
Complex zoning in quartz due to vacuole inclusions
Same as A, with crossed nicols
Quartz grain showing crystal boundaries and core containing abundant inclusions
Quartz crystals elongate normal to wall of vein, crossed by lines of vacuoles
Same as D, with crossed nicols
Lines of vacuoles crossing quartz grains
Linearly arranged vacuoles
Relation of vacuoles to strain twinning
Same as C, with crossed nicols
Lines of vacuoles radiating from sulphide
Granite altered to fine-grained albite
Tubes in quartz radiating out from carbonate
Minute tubes in quartz
Quartz crystal showing twinning in inner and outer zones
Vein of albite crossing older albite crystal
Zonal distribution of sericite in quartz crystal
Detail of A
Original albite of granite veined by quartz and later albite
Spherule of chalcedony in quartz
Zoned carbonate replacing albitized granite
Quartz replaced by chlorite and two generations of carbonate
Early arsenopyrite veined by quartz and fringed by crystals of later arsenopyrite
Same as D, with crossed nicols
Breccia of quartz fragments cemented by carbonate
Fault breccia containing quartz fragments with matrix of mariposite and ankerite
Microbrecciated quartz replaced by carbonate
Saussuritized gabbro replaced by chlorite and albite, with later development of carbonate and chlorite
Mariposite in parallel arrangement in quartz
Rutile in oligoclase
Botryoidal talc replacing quartz
Detail of C, showing contact of talc and quartz
Veinlet of later quartz with opal and chalcedony
Same as A, with crossed nicols
“Headcheese” breccia
Veinlet of clear quartz cutting strain-twinned crystal of older quartz
Same as A, with crossed nicols
Vug filled with opal amid chalcedony
Veinlet containing quartz, chalcedony, and opal cutting opalized granite
Veinlet of later quartz crossing area of microbrecciation
Same as A, with crossed nicols
Veinlet of later quartz with carbonate
Opal containing metallic mineral
Later arsenopyrite fringing earlier
Gold in breccia with opal cement
Opal replacing albitized granite
Pyrite replaced by tetrahedrite
Jamesonite crystals in vug
Needles of jamesonite in quartz
Arsenopyrite along crenulations in quartz
Gold and galena replacing quartz in contact with coarse arsenopyrite; B, Crushed arsenopyrite fringed by gold
Gold replacing fractured quartz
Gold in quartz and carbonate
Specimen showing crinkly banding
Map of a portion of the Sierra Nevada showing major features of Tertiary drainage
Crinkly banding in quartz with later microbrecciation
Crinkly banding with texture suggesting recrystallization
Sericite band crossing single quartz grain
Folded septum of slate between quartz strands
Crinkly banding crossing strain-twinned quartz
Zoned lamellar quartz crystals
Arsenopyrite veined by quartz with growth of quartz crystals outward from face
Fragments of arsenopyrite in quartz
Clustered arsenopyrite crystals veined by quartz
Geologic map of Kate Hardy mine
Sketch map of South Fork, Mugwump, and neighboring mines
Geologic map of vicinity of Oriental shaft
Geologic map of Oriental mine
Geologic sections, Oriental mine
Map of workings of Rainbow mine, Rainbow Extension mine, and Spiritualist tunnel
Map of Sixteen to One mine
Map of workings of Morning Glory, Extension of Minnie D, Minnie D, Lucky Larry, and Eclipse mines
Map of Yellow Jacket, Eldorado, and neighboring mines
Map of workings on Eldorado vein, Eldorado mine
Map of Irelan mine
Map showing principal workings of Plumbago mine
Figures
Map showing location of the Alleghany district, California
Sketch map of outcrops along the Middle Fork of the Yuba River near Jackass Ravine
Section along prospect tunnel south of Irelan mine
Granite dike cutting schistose gabbro, French Ravine
Gold produced from lode and placer mines of the Alleghany district, 1891-1927, and ore mined, 1903-1927
Details of junction of main vein and fault veins, Sixteen to One mine
Map of western part of adit level, Oriental mine
Section showing detail of junction of Sixteen to One and Ophir veins, Sixteen to One mine
Section along vein in Eldorado mine
Sketches showing thrusting in veins
Sections across vein, Plumbago mine
Plan and sections of a part of the Rainbow mine, showing relation of Rainbow and Clinton veins
Section of Sixteen to One vein below drain tunnel
Arsenopyrite veined by quartz
Radiate needles of galena, probably replacing jamesonite
Gold and galena in arsenopyrite
Gold replacing quartz and arsenopyrite
Sketch of Gold Canyon vein, showing occurrence of arsenopyrite and gold
Sketches showing relation of crinkly banding to ribbon quartz
Sketches showing possible folding of vein quartz
American tunnel, Brush Creek mine
Drifts from winze, Brush Creek mine
Sketch map of Finan prospect
Surface geology, Kate Hardy mine
Map of lower tunnel, Tomboy prospect
Sketch map of workings, Oak prospect, Bob Evans claim
Plan of workings of North Fork mine and section along line A—B
Sketch map of accessible workings of Kenton mine
Map of General Sherman tunnel
Plan and section of parts of the 900-foot, intermediate, and 1,000-foot levels, Sixteen to One mine
Map of Ophir mine and adjoining workings of Sixteen to One mine
Map of drain level, Ophir mine
Map of upper tunnel, Extension of Minnie D mine
Map of workings, Osceola mine
Map of workings, Red Star mine
Sketch map of Mayflower prospect
Plan of Dreadnaught tunnel
Map of workings, Docile mine
Sketch map of lower tunnel, Mammoth Springs mine
Sketch map of Mountain View tunnel
Sketch map of Oriflamme tunnel
Sketch map of upper tunnel, Arcade mine
Sketch map of lower tunnel, Arcade mine
Map of Plumbago mine
Map of German Bar mine
Map of Gold Canyon mine
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