Economic Geology

Copyright 2009, Society of Petroleum Engineers This paper was prepared for presentation at the 2009 SPE/EAGE Reservoir Characterization and Simulation Conference held in Abu Dhabi, UAE, 19–21 October 2009. This paper was selected for presentation by an SPE ...

This report documents several new findings concerning the geology and mineral potential of the central East Tintic Mountains, Utah. For example, fission-track ages and 40Ar/39Ar ages which we report suggest that some of the
volcanism and alteration in this area is as old as 37.4 to 35.3 Ma. This early episode of volcanism was contemporaneous with lacustrine deposition; the overlying volcanic rocks and cross-cutting intrusions range in age from about 34.5 to 33.6 Ma. This implies that a large caldera related to the eruption of the younger Packard Quartz Latite and Fernow Quartz Latite is not present in this area . However, our data suggest that a smaller caldera related to the eruption of the tuff member of the Copperopolis Latite may be present. We note that many monzonite dikes and intrusions in this area are hornblende bearing and are correlative in modal and chemical composition with the productive Silver City Stock rather than the barren Sunrise Peak Stock. The large areas of hydrothermal alteration which surround these intrusions
exhibit many similarities to the well-studied alteration halos in the East Tintic District. The age, composition, and field relationships of the post-lacustrine volcanic rocks suggest that they may represent, in part, the extrusive equivalents of the monzonite dikes and Silver City Stock. Our work suggests that the Silver City Stock and related intrusions may be part of one of the youngest (33.6 ± 0.2 Ma) igneous events in the central East Tintic Mountains, but not as young as previously suggested (ca. 31.5 Ma). In addition, our recent work has documented the existence of unusually large (and abundant) magmatic sulfides in lava vitrophyres and vent-facies biotite latite dikes, which are the surface expressions of the Silver City Quartz Monzonite intrusions in this area. In addition, preliminary analytical data suggest that the sulfides host most (-75%) of the Ag present in the latites. The East Tintic Mountains are potentially the first locality, worldwide, where Ag in mesothermal veins can be demonstrated to be derived from degassed Ag-bearing magmatic sulfides. Consequently, the central East Tintic
Mountains are a favorable area for exploration for Ag (Pb-Zn-Cu-Au) ore bodies because: 1) productive monzonite intrusions are present, and 2) Paleozoic rocks favorable for ore deposition may be present beneath relatively thin volcanic cover because the area is not entirely enclosed within a caldera.

LOCATION

11N 17E Sec. 20 SBM 35.02363 -115.17026 (MRDS, 2011)
11N 17E Sec. 20 SBM 35.02082 -115.17022 (MRDS, 2011)

OWNERSHIP
1916

J. C. Kinsman  has installed a Stebbins dry concentrator at Goffs, California, to operate on
tungsten ore from the Signal district (Mining and Oil Bulletin, 1916, p. 143).

1919

Owner: A. L. Lombard and J. F. Main Estate, Goffs, California; office address, 540 I. W. Hellman Bldg., Los Angeles, California (Cloudman and others,  1919, p. 846).

 
1922

Vanadium Gold Company. The following are the officers of the company, having head offices at 310 S. I. Ferry Terminal, New York City: President, L. C. Butler; Secretary. A. E. Post; General Manager, H. W. Evans (Newman, 1922, p. 310).

1930

Lomabard and Main Group, formerly California Vanadium Company (Tucker and Sampson, 1930, p. 294).

1941, 1953

Last reported owners were A. L. Lombard and J. F. Main Estate, Goffs (Partridge, 1941, p. 307; cited in Wright and others, 1953, p. 120).

DEVELOPMENT 

1919

Lombard and Main, formerly the California Vanadium Company, have a large number of claims adjoining the property of the Louisiana California Mining Company and have uncovered a few promising veins. Some development work was done several years ago on gold-bearing veins on this property, and the later work is practically all superficial, several tons of fairly high grade float have been found and treated at the mill lately erected by the owners. The mill consists of Braun roll and a Stebbins dry concentrator. About one ton of concentrates, that is said will average 75% tungstic oxide and are being held for higher market price, have been produced. The dry concentrator is reported to be thoroughly satisfactory for the treatment of this ore. It is operated by a gas engine. Mill was idle when visited, as the owners were doing some rospecting work on their claims (Cloudman and others,  1919, p. 845-846).
1922

The property consists of 10 claims or 194 acres and was discovered in 1902 and worked till 1908, when it was sold to the Laiser Rae Company. In 1911, it was taken over by the Louisiana- California Mining Company, and, in 1912, by the present company (Newman, 1922, p. 310).

It is opened by a series of incline shafts, the deepest of which is 900 feet. A 100-ton concentration plant was erected by the old company, power being furnished by gas engines for both mine and mill. Distillate and tops have been used as fuel. The present company for the last eight months has been developing and blocking out ore, putting in raises and ore chutes and getting ready for active operations. Scarcity of water has been one of the drawbacks in times past, so the present company is developing an additional water supply to enable the mill to run both day and night (Newman, 1922, p. 310).

1941

There was a reported production from the mine in 1915 and 1916. The property is now idle.

Little work was done on the deposit, the development being mostly superficial. A small mill was erected, which consisted of Braun rolls and a Stebbins dry concentrator which were operated by a gas engine (Partridge, 1941, p. 307).

MINE GEOLOGY
1922

The vein is of typical quartz type, outcropping strongly across the surface of the claims, and carries gold, silver and vanadium values (Newman, 1922, p. 310).

1941

The ore is wolframite occurring in veins in granite. High-grade float was found in the vicinity (Partridge, 1941, p. 307).

1953

Wolframite and vanadium mineral in placer materials and in veins cutting granite. Idle (Wright and others, 1953, Tungsten Table, p. 120)

1960

Tishler and others, (1960a) mapped the area of the Lombard and Main Tungsten Group as Quaternary fan deposits (Qf).

2007

Miller and other (2007) mapped the rocks at the Lombard and Main Group as Quaternary alluvial fanglomerate (Qaf) with Miocene volcanic rocks (Tv1) to the north.

LOCATION

15N 11E Sec. 03 SBM 35.4189 -115.80415

Section 4, T.15N, R.11E, SBM. North of Yucca Grove  (Wright and others, 1953, Map No. 510, Talc Table, p. 169).

Location : Section 3, T. 15 N., R. 11 E., S.B.M., about one mile north of Yucca Grove, and 19 airline miles northeast of Baker (Wright and others, 1953, p. 202).

OWNERSHIP

Southern California Minerals Co., 320 South Mission Rd., Los Angeles, California . They own three patented claims (Wright and others, 1953, Map No. 510, Talc Table, p. 169 and 202).

DEVELOPMENT

The Calmasil mine, opened by the present owner in 1940, had yielded about 16,000 tons of commercial talc through 1951. The deposit consists of a lens, 6 feet in average width, which underground workings have followed laterally for a maximum of 200 feet and down-dip for more than 250 feet (Wright and others, 1954, p. 202).

The workings consist of two principal levels. One is reached by a 200-foot southwest-trending crosscut adit, encountering the southeastern end of the deposit, and appended to a 150-foot drift most of which has been removed by stoping. The second level is a 200-foot drift joined to the first by a 90-foot winze steeply inclined to the northwest. The unusual firmness of the walls has permitted mining with very little timber and a recovery of more than 90 percent of the commercial material (Wright and others, 1954, p. 202).

GEOLOGY

Wright and others (1953) gave this description of the Camasil Mine:

The deposit is enclosed by a limestone unit which is part of a complex of metasedimentary and granitic rocks similar to the Archean (?) talc-bearing terrane at the Silver Lake mine described below. The deposit is in a talcose belt several thousand feet long which in, includes the Pomona deposit to the northwest. The Calmasil deposit strikes N. 50° W. and dips steeply northeast. The talc is a blocky to schistose, :fine-grained, white material. Locally it contains a high proportion of tremolite. The deposit lenses laterally into sub-commercial talcose rock (Wright and others, 1953, p. 202).

Greenwood (1984) said this about the Camosil Talc Mine:

Economically significant talc reserves are present at the Yucca Mine with lesser reserves at the adjacent Calmosil Mine (Greenwood, 1984, p. 3).

Greenwood (1984) mapped the area of the Camosil Mine as being located in a mass of Pre-Cambrian rocks with Mesozoic granite (Mzgr) to the south and older Pre-Cambrian rocks to the southwest. Miller and others (2007) mapped the location of the Camosil Mine in their Early Proterozoic Xg unit.

LOCATION

12N 18E Sec. 30 SBM 35.09445999960 -115.08471  (MRDS, 2011)
 
1964, 1987
Location: *E1/2NE1/4, Sec. 25, T.12N., R.17E., and S1/2. Sec. 19 and Sec. 30, T.12N., R.18E., SBBM, San Bernardino Co. (Southern Pacific, 1964/1987; Oesterling, and Spurck, 1964, p. 127-128).
1990
T12N, R.18E, Section 30, SBM (U.S. Bureau of Mines, 1990a, Map No. 595, Table 2, p. 196).

OWNERSHIP
Not reported

DEVELOPMENT

1964, 1987
Description: seven shafts and numerous pits (Southern Pacific, 1964/1987; Oesterling, and Spurck, 1964, p. 127-128).
1990
Numerous pits and several shafts. No known production. The deepest shaft is in excess of 50 feet deep. Recent work resulted in an open pit 300 ft in diameter and 30 ft deep from which material was extracted for heap leaching. A leach pad (200 ft by 100 ft by 1S ft) containing about 20,000 tons of material exists at the property (U.S. Bureau of Mines, 1990a, Map No. 595, Table 2, p. 196).

GEOLOGY OF THE VONTRIGGER HILLS

The geology of the Vontrigger Hills was described by Ted Theodore (1996, p. 121):

Bedrock of the Vontrigger Hills is mostly Early Proterozoic granitoid rocks (unit Xg1, pl. 1), dated between 1,660 and 1,695 Ma, and migmatite (Xm). Small areas of Miocene volcanic rocks (Tv1) and Cretaceous granitoid rocks (Kpg) are found mainly in the western part of the area. Stream-sediment samples from the Vontrigger Hills do not contain anomalous concentrations of any elements. However, concentrate samples have anomalous concentrations of Ag and Ba, and rock samples have anomalous concentrations of Cu, Mn, Pb, Zn, Ag, As, Bi, Mo, Be, B, and Nb. The area is geochemically moderately anomalous overall. Possible deposit types include porphyry copper-molybdenum, polymetallic veins and replacement bodies, and REE-Nb-bearing pegmatites (Theodore, 1996, p. 121).

Six mineral occurrences in the Vontrigger Hills include three polymetallic veins, two low-sulfide gold-quartz veins, and one polymetallic fault (pl. 2). All occurrences are far removed from the Cretaceous granitoid that crops out near the southwest end of the Vontrigger Hills (pl. 1), and all the occurrences are hosted by Early Proterozoic younger granitoid rocks. Mineralization is extremely widespread at some localities (pl. 2), such as in the general area of the Rattlesnake Mine (U.S. Bureau of Mines, 1990a, map no. 592, pl. 1), where numerous prospect pits, shafts, and a partially reclaimed open cut approximately 100 m wide follow favorable indications of gold mineralization of various attitudes and types in an area of about 3 km2. Much of the gold mineralization initially exploited at the Rattlesnake Mine, classified as polymetallic vein, is along a 10-m-wide zone of intensely silicified and highly fractured, foliated Early Proterozoic younger granitoid rocks. This mineralized zone has a strike of about N. 70° W. and is present at the north edge of a porphyritic monzogranite of undetermined size (not shown on pl. 1). Numerous unmineralized porphyritic granite dikes containing K-feldspar phenocrysts cut the Early Proterozoic younger granitoid rocks (Theodore, 1996, p. 121).

MINE GEOLOGY

1956

Hewett’s map (1956) has the Rattlesnake Mine in PreCambrian gneiss and granite (€g)

1960

Tishler and Bonham (1960c) mapped the area of the Rattlesnake mine as Pre-Cambrian Granite – gneiss  (p€gr).
the Rattlesnake mine shafts are associated directly with Quartz monzononite porphyry dikes within the PreCambrian gneiss.

Tishler and others (1960b) said this of the Vontrigger Hills gneissic granite: 

…cropping out in the Vontrigger Hills as well as the Tungsten Flat Signal Hill area is gneissic granite. This granite, which ranges in color from light bluish gray (5 B 7/1) to medium bluish gray (5 B 5/1), is composed largely of coarse orthoclase crystals (1/4" long) in a  sheared and rolled quartz and biotite matrix. In the Vontrigger Hills the granite gneiss is intruded by quartz monzonite porphyry dikes and crushed granite porphyry dikes which are composed of rounded orthoclase, biotite,and sericite (Tishler and others, 1960b, p. 12)

1964, 1987

Geology: gold, chalcopyrite, malachite, and azurite in narrow quartz veins in steeply dipping shear zones that trend NW in gneiss Conclusions: shows limited promise. (Southern Pacific, 1960; Oesterling and Spurck, 1964, p. 128; Tishler and Boham, 1960a, 1960b).

Geology: gold-copper? mineralization associated with alaskite dikes along nearly vertical shear zones that generally strike NW in granite gneiss (Southern Pacific, 1964/1987; Oesterling, and Spurck, 1964, p. 127-128).
1990
Quartz diorite·to·quartz monzonite gneiss occurs with biotite schist and alaskite. A large zone of mylonite exists in the vicinity of the older workings.  (U.S. Bureau of Mines, 1990a, Map No. 595, Table 2, p. 196). 

Twenty samples (CAL·27, 70·80, 93·100) from pits and shafts in the area. No resources calculated. Samples contained up to 784 and 662 ppb gold and >1% copper (U.S. Bureau of Mines, 1990a, Map No. 595, Table 2, p. 196). 

2007

Miller and others (2007) mapped the rocks at the Rattlesnake mine as Younger Proterozoic granitoids (Xg1)

This file is Appendix 02 for the paper "Geology and Mining History of the Cady Mountains, San Bernardino County, California" posted at

https://www.academia.edu/44076044/Geology_and_Mining_History_of_the_Cady_Mountains_San_Bernardino_County_California

The table a listing of mineral deposits by commodity for the Cady Mountains Mining District.

The table is designed to be printed on Tabloid (11 in x 17 in) paper.

The data for this table comes from the U.S. Geological Survey MRDS system (2011).

Investment opportunities in the gemstones business in Nigeria
There are abundant and diverse Investment opportunities in the nascent colored gemstones industry in Nigeria and these include: mining, trading, brokering deals, and processing.
Mining: Mining of coloured gemstones is widespread in the nation and is mainly carried out by Artisans and Small scale Miners (ASM). The artisanal miners are informal mostly migratory and have served as ‘pathfinders’ discovering and temporarily mining many rich deposits of spectacular gemstones.
The government as part of the mining reform established the department of Artisanal and Small scale Miners to organise support and promote ASM. The general economic reforms have created an enabling investment climate with relatively cheap labour.
There are numerous viable opportunities for mining the rich and extensive near surface deposits of sapphire, ruby, emerald, aquamarine, tourmaline, and the rest, which are found in Nigeria and presently under-exploited. Investment in this sector allows foreign ownership or in partnership with local miners.
Trading: The guidelines and conditions for the establishment of private mineral buying centres (MBC) have been developed. Government is embarking on a drive for the registration of MBC nationwide which will provide opportunity for trading companies to establish gem buying centres in any part of Nigeria.
Processing: Since Nigeria is not ‘a consuming nation of gemstones’ much of the gemstone production is being exported rough. Only an insignificant portion is processed locally hence there are great opportunities for tumbling, beading, faceting, carving, and jewellery making in the country.

LOCATION 

5N 12E Sec. 34 SBM 34.48473 -115.72053 (MRDS, 2011)

The Bristol Lake Salt Plant (formerly California Salt, Leslie Chloride Plant) is southeast of Amboy Crater volcanic flows in Bristol Dry Lake. The southeast end of the Bristol Mountains are to the northwest and the America Mne in the northwest Bullion Mountains is to the southwest.

Bristol Lake, recently and thoroughly described by Gale (1951) covers an area of about 60 square miles just south of Amboy. It occupies the center of a broad depression, bordered mainly by ranges of pre-Cretaceous crystalline rocks, but flanked on the northwest by flows of Recent basaltic lava which emanated from ·Amboy crater about
3 miles west of Amboy (Wright and others, 1953, p. 219).

OWNERSHIP

California Salt Company National Salt Company Leslie Salt Company

The land is administered by U.S. Burau of Land Management. Operators leased the salt from the federal government under authority of Saline Placer Act of January 31, 1901 (31 Stat. 745; 30 U.S.C. 162) (The Diggings, 2021).

GEOLOGY

A regional geologic mosaic of the Bristol and Old Dad Mountains is available at:

https://www.academia.edu/s/bd8414fe42/geologic-mosaic-of-the-bristol-and-old-dad-mountains-san-bernardino-county-california-text

A regional stratigraphic compilation for this mosaic is at:

https://www.academia.edu/31570340/Stratigraphic_Compilation_for_the_Bristol_and_Old_Dad_Mountains_San_Bernardino_County_California_TEXT

My report on the geology of the Bristol Lake Salt Plant can be accessed at:

https://www.academia.edu/52331735/Amboy_Crater_Area_Mines_San_Bernardino_County_California 

or

http://www.greggwilkerson.com/amboy-crater.html

LAKE DEPOSIT GEOLOGY

Distribution . The west edge or the map area is occupied by Bagdad  Dry Lake, which is the western extreme of lake deposition in Bristol Basin.  Bristol Dry Lake is situated south of Amboy in the eastern half of the  area (Schaefer and others, 1958. p. 7-8). 

Lithology. The playa surface consists of tan to dark brown clay containing scattered gypsum crystals along the lake margins. The clay surface is very rough consisting of puffy hummocks which is characteristic  type of playa clay. This feature is due to the salt content of the clay which commonly produces a “salt bloom due to  capillary action. In places, on Bristol and Bagdad Dry Lakes, there is a  very thin crust of salt . This has been deposited by the evaporation of surface runoff water which in wet years may lie standing on the lake to a  depth of several feet (Schaefer and others, 1958. p. 7-8). 

Gypsum occurs in a belt around the north and west sides of Bristol dry Lake. On the geologic map an area of dominantly gypsum (as determined  by field observations and air photo geology) and another of gypsiferous clay are distinguished. Core hole data (see APPENDICES B and C) indicate the subsurface extent of the gypsum is variable (Schaefer and others, 1958. p. 7-8). 

Subsurface data in the lake center (see APPENDICES D and E and Gale,  1951) show that Bristol Basin is filled with over 1000 feet of alternating  beds of salt , clay, and silt . The uppermost and mined bed of salt is  outlined on the map (data from Gale, 1951). The core data indicate the  salt is associated with green beds of clay. This relationship indicates that a fairly persistent body of water existed during deposition of  the green clay and then it desiccated enough to deposit the salt. Origin  of the salt is not definitely known (Schaefer and others, 1958. p. 7-8). 

Age and Relation to other rocks. There is evidence of deflation having removed sediment from the surface of the dry lake. This and the veneer of eolian sand (thick in places but not shown on geologic map) along the west side of the playa gives the impression that the basalt overlies the lake clay. Actually, the basalt is overlain partly by the dry lake beds, but the subsurface relationship is not known. It is  assumed that the flows lie upon older lake sediment. Alluvial material around the sides of the playa overlie and extend in places out onto the dry lake (especially southeast of Saltus) (Schaefer and others, 1958. p. 7-8). 

The lake deposits are considered to be Pleistocene in age, but may extend to the sub-Recent (Schaefer and others, 1958. p. 7-8). 

Bishop (1963) mapped the Bristol Lake Salt Plant as having outcrops of:

Holocene deposits

Qlt: Salt Deposits
Ql: Quaternary lake deposits
Qpvb: Pleistocene basalt
Quaternary and/or Pliocene cinder cones

Bishop (1963) mapped the area of the Bristol Lake Salt Plant as salt deposits (Qst) within Quaternary lake beds (Ql).

Kupfer and Basset (1962) mapped the following units in the Bristol Lake Salt Plant area:
Qa: Alluvium
Playa Deposit
Qca
Qx
Qxb
Qxc
Qxg

Qoa: Quaternary Older Alluvium
Qb2: Quaternary basalt flows and cones

Kupfer and Bassett, 1962, mapped the area of the Amboy Crater Mines as
Quaternary basalt flows and cones (Qb2).

Kupfer and Bassett (1963) mapped the Bristol Lake Salt Plant as a salt crystal body at or near the surface (Qx):

Bedford and others (2010) and Phelps and others (2012) mapped the Amboy 100K Quadrangle. Howard (2002) mapped the Sheep Hole 100K Quadrangle. In the Bristol Lake Salt Plant area they identified the following units:

Substrate Units: Qmv: Quaternary Mafic Volcanics


Hill Slope Deposits
Qha/Qmv

Alluvial Units
Qya

Wash Deposits
Qyw-Qaw: Young Wash-Active Wash deposits

Pediment Surfaces
Qpd-fpg: Deeply dissected pediment, felsic plutonic rocks converting to gruss
Qpi/pc: Incised pediment, partly consolidated

Eolian Deposits

Qye/Qmv: Young eolian sand/Quaternary mafic volcanics
Qae/Qmv: Active eolian sand deposit/Quaternary mafic volcnics

Qyp: Younger playa deposit
Qpsg and Qpsh: Halite and gypsum deposits

Bedford and others (2010) mapped the area of the Amboy Craters as Active eolian sand deposit/Quaternary mafic volcanics (Qae/Qmv) and Hillslope/Quaternary mafic volcanic rocks (Qha/Qmv).

Howard (2002) mapped the area of the Bristol Lake Salt Plant as Quaternary Playa silt-halite deposits (Qpsh).
Dibblee and Minch (2008f) mapped the area of the Bristol Lake Salt Plant as having the following exposures:

Qa: Alluvium

Qoa: Older Alluvium

Qb: Pleistocene basalt

Dibblee and Minch (2008f) mapped the area of the Amboy Craterss Area  as Quaternary basalt (Qb). There map does not extend to Bristol Dry Lake.

Schafer and others (1959): T.5N, R.11 and 12E, SBM:

Qal: Alluvium
Qabf: Recent basalt flows
Qabcc: Younger cinder cones

Bristol (Dry) Lake sediments:

EVAPORITES

In the area of the Bristol Lake Salt Plant, Schafer and others mapped lakebed halite and clay (Qblh).

Schafer and others )1958) described saline minerals in Bristol and Cadiz lake in their Southern Pacific Railroad report for T.5N, R.11 and 12E, SBM. The Saline Mineral section of that report is reproduced in Appendix A.

The rock salt deposit of present commercial interest is an extensive horizontal layer as much as 7 feet thick, and covered by 3 to 7 feet of overburden. It is believed possible to mine the salt profitably over an area of 5 square miles in the northwestern part of the lake where the salt layer exceeds 3 feet in thickness. Bordering this area on the south is the depression's lowest part, known as Salt Lake and covered with a thin crust of rock salt. Plants recovering calcium chloride from the brines of Salt Lake have produced common salt as a by-product (Wright and others, 1953, p. 219)

LOCATION

13S 6E Sec. 29 SBM 33.01228000030 -116.39167000000

This gold prospect is in the SW1/4SW1/4 of Section 24, T.13S, R.5E, SBM; Anza-Borrego Desert State Park, about 11 miles east-south east of Julian, at base of southeast flank of Oriflamme Mountains (Weber, 1963, p. 165). The deposit is on a Quake hill between Little Blair Valley and Blair Valley.

OWNERSHIP

Ownership was undetermined in 1957 (Weber, 1963, p. 165).

DEVELOPMENT

A 25 foot deep shaft is inclined steeply east in biotite quartz diorite. Probably no production (Weber, 1963, p. 165).

GEOLOGY

Weber’s map shows this mine to be in undivided Cretaceous granitc rocks (Kgr).

The geology of the area was mapped by Dibblee (2008e, 2008f) as Mesozoic or older basement complex granite. (bc-gr).

The present study deals with two primary aims; (1) geological, mineralogical, and geochemical investigations of the Deh Hosein, Astaneh, and Nezam Abad mineralizations in the Astaneh-Sarband area, west central Iran, with the aim to understand the characteristics of the occurrences and their conditions of formation, and (2) geochemical investigations on ancient bronze artifacts from Iran and Western Asia in order to compare their characteristics with the high-tin copper ore of Deh Hosein and examine their possible relationship.
The Astaneh-Sarband area is located in the northern part of the NW-SE aligned Sanandaj-Sirjan metamorphic belt and consists mainly of Mesozoic schists, Middle Jurassic to Middle Tertiary intrusive rocks and related contact metamorphic aureoles, and pegmatites. Regional metamorphism in the area has reached a peak of greenschist facies, but further metamorphism has occurred locally, associated with granitoid emplacement. Magmatism has produced large felsic to intermediate intrusive bodies along a general northwest trend. The main trend of the faults, fractures and other structural features of the area is NW-SE.
The Deh Hosein prospect is mainly hosted by Jurassic meta-sedimentary rocks, which have been intruded by the Astaneh complex. Mineralization continues into the southern part of the Astaneh intrusion. The meta-sedimentary rocks consist of alternating meta-sandstone, phyllite, schist, spotted slate and hornfels. The main faults and other structural features, with NW and NE trends, have controlled the mineralization, which occurs in the form of quartz, quartz-sulfide and quartz-gossan veins and veinlets, partly sheeted in structure. These veins are up to 1.5 m wide and several to tens of meters long. Mineralization also occurs as disseminations and impregnations, especially in the vein selvages. Adjacent to and within zones of intense quartz veining, the predominant alteration assemblage is quartz + sericite + tourmaline + monazite. Some 35 metalliferous minerals have been detected at Deh Hosein. Arsenopyrite is the dominant sulfide mineral, with lesser amounts of chalcopyrite > pyrite > pyrrhotite. Cassiterite and ferberite are the rather abundant oxide minerals. The sulfide content in the ore is generally less than two volume percent. Arsenopyrite associated with early alteration and veining typically contains 1-150µm large inclusions of native bismuth, bismite and bismuthinite. Gold occurs in “invisible” form in the arsenopyrite and bismuth-bearing minerals of Deh Hosein. Bulk gold contents determined by NAA in the ore ranged from 0.05 to 13.3 ppm, while the Cu, Sn, W, and Bi concentrations of veins range up to 10%, 6.7%, 2420ppm, and 1800ppm, respectively.
At Astaneh, gold mineralization is confined to the NW-SE trending Astaneh intrusion that is composed mainly of biotite granite (98.9 ± 1.0 Ma; Masoudi 1997), which is locally accompanied by granodiorite, tourmaline granite and quartz diorite. The northeastern part of the Astaneh intrusion has been cut by the Shirmazd granodiorite. This stock is about 400 m in diameter and Eocene in age (Rb/Sr and single zircon evaporation methods, this study). The Shirmazd granodiorite has been cut by NE-trending microgranodiorite dykes. Gold mineralization occurs mainly as NE-trending quartz- and quartz-sulfide veins and veinlets, as well as in disseminations in the Shirmazd stock and the intersecting microgranodiorite dykes, and in some nearby, smaller, altered granitic stocks. Alteration minerals include sericite, chlorite, quartz, calcite and in some cases kaolinite. At Astaneh chalcopyrite and arsenopyrite are the major sulfide minerals, of which the latter contains 1-50 µm sized inclusions of native bismuth and bismite. Gold occurs in both visible and invisible forms at Astaneh. Visible gold has been reported in the form of very fine grained particles (<15 µm) either in goethite produced from the oxidation of chalcopyrite or in sericitized plagioclase (Hashemi 2002), while invisible gold occurs in arsenopyrite and bismuth-bearing minerals. Bulk gold contents determined by NAA ranged from 0.05 to 9.5 ppm, while the Cu, Sn, W, and Bi concentrations of veins range up to 1%, 0.05%, 100 ppm and 138ppm, respectively.
The Nezam Abad mineralization is hosted by a Lower-Mid Eocene quartz diorite unit. This rock unit has been cut by several aplitic and quartz or quartz-tourmaline veins; the latter host the mineralization. The faults of the area are NW-, NE- and N-trending. Associated alteration minerals include quartz, chlorite, sericite, and tourmaline. At Nezam Abad, chalcopyrite, arsenopyrite and scheelite are the most abundant ore minerals. Gold occurs as “invisible” form predominantly in arsenopyrite with bismuth inclusions at Nezam Abad. Bulk gold contents determined by NAA ranged from 0.05 to 36.2 ppm while the Cu, Sn, W, and Bi concentrations of veins range up to %10, %0.87, %3.37 and 548ppm, respectively (Farhadian 1999).
In all three occurrences, gold shows positive correlations with arsenic, bismuth, selenium, silver, tellurium and antimony. Microprobe investigations revealed that the arsenopyrites from Deh Hosein, Astaneh and Nezam Abad contain 32.3 to 34.3, 30.7 to 31.4, and 33.6 to 35.6 atomic percent of arsenic. Average compositions lead to the conclusion that the mineralization formed at temperatures of 460°C, 410° to 380°C and 565° to 510 °C, respectively. Oxygen isotope ratios for gold-bearing quartz veins in the area range from 13.6 to 19.2‰ for Deh Hosein, from 11.5 to 13.7‰ for Astaneh and from 11.6 to 15‰ (V-SMOW) for Nezam Abad. The oxygen isotope data suggest a metamorphic or a mixed magmatic-metamorphic source for the quartz veins. Measured sulfur isotope values for pyrite, chalcopyrite, galena and arsenopyrite in quartz veins of the Deh Hosein, Astaneh and Nezam Abad range from -5.6 to 0‰, -0.5 to 1.8‰ and 1.2 to 4‰ (CDT), respectively. The sulfur-isotope values of all these occurrences are compatible with a magmatic sulfur source. Pb isotope ratios from the sulfide and host rock samples of the prospects indicate a good agreement between the lead ratios of the ore of Deh Hosein and the hosting meta-sandstone, the ore of Astaneh and the Shirmazd Stock and the ore of Nezam Abad and the hosting quartz diorite. The Pb isotope signatures of the ore from the three occurrences show also rather close ratios. According to the plumbotectonics model of Zartman and Doe (1981) the lead in the ores has a lower crustal Pb component.
The studied occurrences share several similarities in terms of their mineralogy, geochemistry, formation temperatures, isotope ratios, alteration and occurrence of gold. They also indicate many similar features with the “intrusion-related gold systems” that have been described from Alaska, the Yukon and other parts of the world (e.g., Lang et al. 1997, 2000; McCoy et al. 1997; Thompson et al. 1999). According to the present data, it appears that a fertile magmatic source (probably of lower crustal origin) has affected the already present metamorphic rocks of the area (by remobilizing some of their elements) and caused a rather intensive gold mineralization in the area during the Pyrenean Orogeny.
The extensive ancient mining relics at Deh Hosein, the simultaneous occurrence of tin and copper in it, together with frequent archaeological and ancient textual references which refer to the Iranian plateau as supplier of the raw material for the ancient Mesopotamia and southwestern Iran (Susa and Luristan) encouraged me to examine the possible relationship between the ore of this ancient mine and the ancient bronze artifacts. For this purpose, several bronze artifacts of typical Luristan style which date most probably to the Iranian Iron Age (from about 1300-1250 to 650 BCE) were investigated. The results were compared to the analyses of the Deh Hosein ore and other bronze artifacts previously published. Examination of 29 bronze artifacts from Luristan by energy-dispersive X-ray fluorescence analysis revealed that the Luristan bronzes show variable concentrations of As, Pb, Zn and Fe in addition to high concentrations of tin (0.48-15.4%). The ore composition of Deh Hosein is matched by several bronze artifacts from Luristan analyzed in this study as well as in previous investigations (Fleming et al. 2005). Even more noteworthy is the observation that the lead isotope ratios of the ore samples from Deh Hosein are in very good agreement with 25 samples of metal artifacts from Luristan and other bronze artifacts dated to the third millennium BCE from the southern Persian Gulf (Weeks 1999), the Aegean (Begemann et al. 1992), as well as from third millennium BCE sites in Luristan and Mesopotamia (Begemann & Schmitt-Strecker in preparation).
At Deh Hosein, which is located at the western rim of the Luristan area and is close to ancient civilization centers of Susa and Mesopotamia, the ancient workings appear as numerous big ellipsoidal open depressions in two rows along the mineralized horizons. The old workings are up to 70 by 50m in size and up to 15m deep and are aligned over some 500m. Several hammer stones of silicified phyllite and granite, pottery shards and grinding stones have been found in the open-cast mines and adjacent ancient settlements. The pottery shards can be dated to the early first millennium BCE. Pieces of charcoal found in one of the diggings yielded a radiocarbon date of 3380 ± 55, which on calibration (2 sigma) results in an age range of 1775-1522 BCE.
Several indications attest that Deh Hosein has been a major supplier of tin for ancient civilizations of Iran and Mesopotamia and perhaps even further west beginning in the third millennium BCE.
In summary: i) The lead isotope compatibility of ores from Deh Hosein with many bronze artifacts from Bronze and Iron Age sites distributed from the southern Persian Gulf to the Aegean is good. ii) This is combined with a good match for trace element patterns of ores and artifacts. iii) Copper and tin occur within one mineralization. iv) Ancient textual references mention tin and bronze supply from regions east of Mesopotamia. v) The dating of surface finds of pottery and charcoal finally supports these findings. At present Deh Hosein is the only known copper-tin occurrence close to Luristan and Mesopotamia.
The northern part of the Sanandaj-Sirjan zone which is characterized by intrusion of several intrusive bodies in metamorphic terranes favors the occurrence of similar deposits as in the Astaneh-Sarband area. Thus, the prospects are good for further exploration in the region which may also reveal some other ancient mines.

Keywords:
Deh Hosein (Deh Hossein) Deposit, Nezam Abad Deposit, Astaneh Gold Deposit, Astaneh-Sarband (Shazand) area, Arak, Iran, Intrusion-Related Gold System

كليدواژه ها                                                                       
كانسار ده حسين، كانسار طلاي آستانه، كانسار نظام آباد، منطقه آستانه-سربند (منطقه شازند) اراك، سيستم هاي كاني سازي طلا مرتبط با توده هاي نفوذي، فلزكاري و معدنكاري كهن، مفرغ هاي باستاني لرستان، مطالعات ايزوتوپي

Mother Lode: Geology and Mining History: Legend to Geologic Maps

This legend is for the regional maps in my three-part guidebook series “Geology and Mining History of the Mother Lode”

Part I: Mariposa to Jackson
https://www.academia.edu/33103070/MOTHER_LODE_Ia_ROADSIDE_GEOLOGY_AND_MINING_HISTORY_MARIPOSA_TO_JACKSON_TEXT

Part II: Jackson to Grass Valley
https://www.academia.edu/33102851/ROADSIDE_GEOLOGY_AND_MINING_HISTORY_OF_THE_MOTHER_LODE_II_TO_GRASS_VALLEY

Part II: Grass Valley to Taylorsville
https://www.academia.edu/33102890/ROADSIDE_GEOLOGY_AND_MINING_HISTORY_OF_THE_MOTHER_LODE_III_GRASS_VALLEY_TO_WALKER_BASIN

I have produced regional maps for this guidebook series at a scale of 1:50,000. They are designed to be printed on Arch E size poster paper: 36” x 42”.

The maps were created by overlaying the U.S. Geological Survey Digital Geologic Map for California with the ESRI-based U.S. Geological Survey topographic map compilations (2021).

The set of regional maps are:

R-01: Mariposa to Moccasin
R-02: Coulterville to Fourth Crossing
R-03: Eagle Shamut to Chilton Peak
R-04: Copperopolis to Plymouth
R-05: Amador to Garden Valley
R-06: Coloma to Nevada City
R-07: Nevada City to La Porte
R-08: Goodyear’s Bar to Quincy
R-09: Blackhawk Creek to Bassetts
R-10: Bassetts to Walker Mine

LOCATION
35.82167 -115.54917 24S 57E Sec 35 (MRDS, 2011)
35.8214 -115.55084 24S 57E Sec 35 (MRDS, 2011)
See Hewett, No. 33, Plate 30

The workings of the Copper Chief mine (No. 33, pl. 30) lie about 1,000 feet west of those of the Mobile (Hewett, 1931, p. 120).

The Copper Chief MRDS location is 330 feet from the U.S. Geological Survey topographic map location for the Shenandoah Mine. The Smithsonite Mine is 935 feet to the north-northwest of the Copper Chief Mine. The eastern MRDS location for the Copper Chief Mine is 725 feet west of the Mobile Mine. The Copper Chief is part a series of mineral surveys.

OWNERSHIP
During 1921, R. Munzberg and H. Hardy .mined or sorted from the dump three lots of ore (Hewett, 1931, p. 120).

COPPER CHIEF MINE DEVELOPMENT

The…[Copper Chief Mine ]includes several short tunnels and shallow shafts which explore minor fractures in the Bullion dolomite. these workings have probably yielded some copper ore,. but they are particularly interesting .as a recent source of cobalt ore. During 1921.R. Munzberg and H. Hardy .mined or sorted from the dump three lots of ore, which, when sold, yielded the returns given below (Hewett, 1931, p. 120):

Total production in 1921 consisted of  about 2,569 lb cobalt oxide and probably some copper. Hewett, 1931, p.  120; Barton and Behre, 1954, p. 58 (Longwell and others, 1965. P. 198).

GEOLOGY OF THE COPPER CHIEF MINE

Most of the copper deposits occur in Devonian or earlier rocks, although a few, such as the Ninety-nine and the Doubleup, occur as high in the section as the Bullion dolomite. Only in a few places, as in the Copper Chief, Alice, and·Mobile mines do copper, lead, or zinc deposits occur near by at the same horizon. Most of the copper deposits lie near the belt of granite porphyry intrusions that occur above the Keystone overthrust (Hewett, 1931, p. 92)

In contrast· to that· produced at the Columbia and Highline mines, the cobalt oxide from the Copper Chief was intimately intergrown with brown chert (Hewett, 1931, p. 120).

On Hewett’s 1931 geologic map, and Plate 30, the Copper Chief lies between and south of the Mobile and Shenandoah mines. The Copper Chief is near he junction of a northwest-southeast fracture and a west-northwest-east-southeast fracture in Monte Cristo Limestone. To the south of the mine is Sultan Limestone.

MINERALOGY

Hewett, 1931During this investigation care was taken to note the presence of black minerals, and many speein1ens were tested with the blowpipe, with the result that heterogenite is now known to exist in most of the copper deposits. The purest material consists of the black mammillary crusts or stalactites found on the Blue Jay, Copper Chief, and Colun1bia claims, but these are not abundant (Hewett, 1931, p,. 84).

Stainierite, malachite, and chrysocolla are  common. Anomalous radioactivity associated with siliceous limonite and chrysocolla (Longwell and others, 1965, p. 189).

LOCATION

35.84417 -115.49501 (MRDS, 2011)
35.8425 -115.49694 (MRDS, 2011)

Section 20 and 29, T. 24 S.,R. 58 E (Longwell and others, 1965, p. 186, table).

The Alice (Yellow Pine Extension) Mine is 2,500 feet south of the Yellow Pine Mine and 4,500 feet southeast of Shenandoah Peak on the eastern flank of the Spring Mountains.

DEVELOPMENT

Intermittent production from 1909 to 1924. Total production equals: 1, 528,851 lb zinc, 46,600 lb lead, 30,933 lb copper, 1,141 oz silver (Hewett, 1931, p. 138-139).

GEOLOGY

The bodies of the Yellow Pine and Alice mines are tabular pipes (Hewett, 1931, p. 93).

The main shaft is sunk in beds of the Bird Spring formation that lie 100 feet or more above the base. In this area they are largely converted to dolomite. Even though they strike generally northwest and dip southwest, they are locally folded and much faulted. At three places in the mine sill-like masses of granite porphyry have been met. The shoots that have been the sources of ore underlie a persistent wall that lies only a few feet above the middle of the sills. In a broad way the wall conforms with the bedding; locally it cuts across it (Hewett, 1931, p. 138).

The Alice mine has a nearly continuous ore shoot 900 feet long, up to 40 feet wide, and 2 to 5 feet thick in dolomite in the basal Bird Spring Formation. Hydrozincite was the ore mineral; aurichalcite, cerussite, and a vanadate were common; galena was uncommon (Longwell and others, 1965, p. 186)

LOCATION

14S 5E Sec. 33 SBM 32.91673000020 -116.46751000000 (North Sundown Mine, MRDS, 2011)
14S 5E Sec. 33 SBM 32.90365999970 -116.46834000000 (South Sundown Mine, MRDS, 2011)

The MRDS locations for this mine are 0.3 miles north and 0.6 miles south of the location for the Sundown Mine as noted on the USGS topographic map. The mine is 0.75 miles northwest of the Penny Pines village site.

The Sundown Tungsten mine is in the NE 1/4 Sec. 33, T. 14 S., R. 5 E., S.B M. about four miles northwest of Mount Laguna, and about one-fourth mile west of Sunrise highway.

OWNERSHIP

The area of the Sundown Mine includes part of Patent 5443 (CACA 088581) for 160 acres that was issued to John A Trimmer on March 24, 1999 under authority of the 1820 Sale Cash Entry law (3 Stat. 566)

The ownership circa 1963 was Patrick Sutherland, Box 172, Descanso, California. The mine was leased to Jack Jarvis. Route 2, Box 566, Lakeside, California (about 1955). In 1943 the property comprised two patented claims (Weber, 1963, p. 274, 280).

DEVELOPMENT

The Sundown Tungsten Deposit, discovered in 1941, was worked almost continuously from that date through part of 1942, and intermittently as late as 1954. Total output from the mine is probably about 150 units of tungsten trioxide (WO3). The ore mined was milled on the property (Weber, 1963, p. 274, 280).

The deposit was prospected originally by means of a 65-foot shaft, inclined 70° north, which was deliberatelv caved in 1947. On the 20-foot level of this shaft a drift trended eastward for about 30 feet, and at the end of the drift a crosscut extended about 20 feet to the north. Both of these workings were in ore. Two drifts that trended westward from the 20- and 65-foot levels, which were 10 and 20 feet long respectively, were not in ore. More recently opened workings consist chiefly of an east trending open cut, whose maximum depth is about 15 feet, and shorter cuts at each end, forming an H-shaped excavation. (Webb, 1963, p. 274, 280).

GEOLOGY

The deposit consists of a body of scheelite-bearing tactite whose lateral extent is obscured by a veneer of alluvium. The underground workings show an east-trending tactite body at least 150 feet long and as much as 20 feet wide, which dips 65° to 70° north. The body is enclosed in hybrid rocks that consist of quartz diorite and schist. The tactite is composed essentially of quartz, garnet, and epidote. Ore mined in 1942 was reported by the operators to average more than 1 percent tungsten trioxide (WO3).  The deposit is noted for rather large scheelite crystals which were recovered from near-surface workings in a very friable, brecciated quartz-garnet rock. One specimen from the deposit contained a broken scheelite crystal two inches in maximum dimension (Weber, 1963, p. 274, 280).

The southern mine MRDS location is mapped as hornblende quartz diorite by Dibblee (2008f) and the northern mine MRDS location is mapped as hornblende diorite to gabbro.  The topographic map shaft symbol is in metasedimentary rocks. This is a more likely location for the deposit, based on its geologic description as a tactite.

The Tethyan-Eurasian Metallogenic Belt, stretching nearly 10,000 km across southern Europe through Anatolia and beyond into Asia is host to a wide variety of mineral deposits, particularly porphyry and epithermal style mineralization.  The Efemçukuru low sulfidation, vein-hosted, epithermal gold deposit located southwest of Izmir, western Turkey is one such deposit and contains a measured and indicated resource of 5.89 Mt grading at 8.71 g/t Au.  The deposit comprises two separate mineralized quartz-rhodochrosite veins: Kestanebeleni and Kokarpınar which dip moderately E- to NE, respectively.  The veins are hosted in an Upper Cretaceous ophiolitic mélange sequence (Bornova Flysch) which is metamorphosed to phyllite and schist on the deposit scale, and occur adjacent to fine-grained quartz phenocrystic rhyolite dikes that dip to the NE.  An aureole of hornfelsed phyllite and schist occurs within a 250-500 m wide zone around to the veins and rhyolite dikes. 
The vein mineralogy is variable but consists primarily of colloform-banded quartz, rhodonite (commonly replaced by rhodochrosite), adularia, and axinite with sulfide assemblages comprising pyrite, sphalerite, galena, chalcopyrite, and minor tetrahedrite.  Alteration related to epithermal veins is variable depending on the host rock type, but is typically dominated by muscovite, chlorite, and halloysite in the schist and phyllite, actinolite and epidote within the hornfelsed rocks, and minor illite in the rhyolite dikes.  Four main styles of Kestanebeleni veining are identified on the basis of mineralogy and texture, each with several subclasses and distinct paragenetic sequence.  Gold is found in the later stages of rhodonite veins and as inclusions in disseminated pyrite and galena in late-staged sulfide and sulfide base metal veins.  The southern part of the Kestanebeleni vein contains significantly more quartz and rhodonite with lesser, and narrower sulfide and base metal veinlets.  The central and northern segments of Kestanebeleni typically have more rhodonite while sulfide veins are wider, coarser-grained, and more dominant at depth.  Structural mapping of the area identified two main sets of normal faults:  I) NE-dipping faults often with SW-dipping conjugate faults and II) cross-cutting NW-dipping faults associated with SE-dipping conjugate faults.  Several distinct structural domains of foliation direction (S1) can be explained by local scale folding and syn- to post-mineralization faulting.  The difference in strike direction between the two main mineralized veins can be explained by relay zones linking major faults during progressive regional extension.  The structural geometry and mineralization style of the Efemçukuru system may be analogous to other potential epithermal systems within the regional extensional regime.

This file is an Arch E size map showing the locations of 720 mines in the study area for this guidebook. The map is at a scale of 1:120,000.

Details about these 720 mines are found in Table 4A and 4B of this guidebook.

For links to other documents and maps in this guidebook go to http://www.greggwilkerson.com/death-valley.html

Acrophobia is a an irrational fear of heights. The phobia is classified by space and motion discomfort, this fear has many root causes and can be severe in its intensity. The present study was carried out to know the degree of the acrophobia among 8th to 10th Government high school students. The response was taken from 2743 students (Male: 1589. Female: 1154). The study found that out of the total male students, 21.63% students expressed the phobia and it is 16.99% in the case of female. Comparatively, high percentage of male students has acrophobia than female students in all the classes. Homeopathy, Exposure based therapy, Cognitive therapy and Relaxation techniques are some of the useful treatment methods.

The northern Lava Bed Mountains, northeast of the Calico Fault are mostly Quaternary lavas with some Pliocene intrusive volcanic rocks. The intrusive relationships are instructive in Sections 24 through 35 of T.7N, R.5E, SBM. Here in sections Tertiary dacite porphyry has invaded older quartz monzonite along a structural grain that results in remnant dike-like masses of quartz monzonite with the dacite porphyry to the east and dikes of dacite porphyry in the quartz monzonite to the west.  Along this same structural grain, Tertiary andesite porphyry invaded dacite porphyry to the east and quartz monzonite to the west.

The central part of the Lava Mountains, between the Calico and Emerson Faults is mainly biotite quartz monzonite with mafic dikes.

The southern part of the Lava Mountains, southwest of the Emerson Fault are Quartz Monzonite of Emerson lake and biotite diorite

The Northern Bullion-Lava Mountains area can be divided into 8 sections by major faults which trend NNW-SSW. They are designated Blocks I to VIII. These fault blocks have sets of secondary sheer faults within them, most of which have right lateral separation. Tension gashes form between the secondary sheer faults and are loci for the formation of vein deposits.

Laboratory and field measurements were made in a study of a small number of chromite deposits in the Josephine ultramafic complex of northwest California, to examine their physical properties and to search for possible diagnostic geophysical signatures. Though the sample was small, the results show that no single geophysical method gives  unequivocal identification of buried massive pods of chromite, but that a combination of gravity, magnetics, and seismics, and complex resistivity might be used to explore successfully if used in a systematic fashion. Some of the geophysical signatures appear to be secondary or associative in nature, raising the possibility that a specific method or combination of methods might have to be modified for application in
an area other than where they were developed.

This map is a georectified mine map with land status for the paper "Geology and Mining History of the Cady Mountains, San Bernardino County, California" posted at

https://www.academia.edu/44076044/Geology_and_Mining_History_of_the_Cady_Mountains_San_Bernardino_County_California

The map is designed to be plotted at for Arch E size (36 in x 42 in) at a scale of 1:50.000

The data for this map comes from the U.S. Geological Survey MRDS system (2011), U.S. Bureau of Land Management, and ESRI.

This Mine Group has 19 mines and prospects listed in Table 1 (from MRDS, 2011).

LOCATION

The Cactus mine is located in Sections 8, 9, 16 and 17 of T.10N, R.18W, SBM. 9 miles southwest of Mojave, Kern County California

HISTORY

Gold was first mined at Middle Buttes in 1894 (Troxel and Morton. 1962) and a group or small mines continued operating there until 1910. Mining activity at Middle Butte resumed during the Depression and was continuous from 1931 to 1942 when. during World War II. gold mining was banned by the federal government.  War Production Board Limitation Order L-208 halted operations at Middle Buttes and all other gold mines in the United States because gold mining was deemed non-essential to the war effort (Burnett and Brdey, 1990, p. 85).

In 1979 the Cactus mine property was acquired by CoCa Mines Incorporated of Denver. Colorado. Commercial production started in August 1986. Gold production reached 26,400 ounces in 1987, and the current annual output (1990) is about 60.000 ounces of gold. Total projected production will be about -400,000 ounces (Burnett and Brdey, 1990, p. 85).

AREA GEOLOGY

The western Mojave Desert is a structural block bounded on the southwest by the San Andreas fault zone and bounded on the northwest by the Garlock fault zone (Figure 1, Burnett and Brady, 1990). Both fault zones are vertical breaks in the earth ·s crust that have undergone significant lateral offset (Dibblee, 1967). The Garlock fault. the closest of these two regional fault zones to the mine. is several miles north of the Cactus mine. Major geologic structures within the mine area. such as northeast-trending ore veins. run parallel to the Garlock fault zone and suggest a regional relationship (Burnett and Brady, 1990, p. 86).

Although Cretaceous granitic rocks and Miocene volcanic rocks are the only exposed units within the mine area. nearby outcrops include several types of metamorphic rocks. Tertiary sedimentary rocks, and Quaternary basalt flows and sediments. These diverse rock types indicate that this region has been tectonically active in the geologic past (Burnett and Brady, 1990, p. 86).
.

Dibblee and Minch (2008b) mapped the Middle Buttes-Cactus Queen Group as mostly Miocene Gem Hill formation (Tgf). There is a small outcrop of Jurassic-Cretaceous Quartz Monzonite (qm)at the northeast edge of Middle Butte. The Butte is surrounded by Holocene Alluvial materials (Qa) and windblown sand (Qs).

Stejer (1958) mapped the area of the Elephant Butte-Standard Hill Group as Alluvial deposits (Qal), Gen Hill Formation (Ttgu), Bobtain Quartz Latite (Tbql) and Quartz Monzonite (JKqm).

The USGS (MRDS, 2011) classified the Middle Buttes (Cactus) Deposit as Ore Deposit Models 104 (Hot-spring Au-Ag) and 151 (Epithermal vein, Sado).

STRUCTURE

The Middle Butte-Cactus Queen Group is in the northern part of Tectonic Block A which is bounded on the southwest by the Tyler-Horse Fault and on the northeast by the Mojave-Edwards fault. It lies to the ease of a secondary “Lazy S” fault.

Quartz monzonite forms the basement rock beneath the mine site and is overlain by lavas and pyroclastic flows. The quartz monzonite formed between 85 million years ago and 112 million years ago and is a granite-like rock containing equal amounts of orthoclase and plagioclase feldspars. Intrusive igneous domes form a semi-circular feature extending from Middle Buttes and Soledad Maintain on the north to Tropico Hill and Willow Springs Hills on the south semi-circular feature ma; represent a caldera that formed when a series of concentric fractures resulted from a collapsing volcano (Figure 2, Burnett and Bradly, 1990, p. 86).

MINE GEOLOGY

The richest ore at Middle Buttes is localized along northeast-trending fault zones. One such mineralized fault zone contains the Cactus vein that was the focus of mining activity in the 1930s. This particular fault zone also hosts the Shumake pit deposit that is was being mined in 1990 (Figures 3 and 4 of Burnett and Bradly, 1990, p. 87). Other ore zones at the mine occur on parallel northeast-trending faults. These mineralized fault zones in turn are intersected by northwest- trending cross-cutting faults; significant amounts of ore are found in fault breccia along these northwest-trending zones (Burnett and Brady, 1990, p. 86).

MINERALOGY

Although in this district, gold is the chief mineral in value, silver is predominant by a 5: 1 ratio and is an important by-product of the gold ore. Cerargyrite (AgCl) and argentite (Ag2S) are the most common silver minerals in these veins, but some ores also contain pyrargyrite (Ag,SbS3 ), native silver, stromeyerite (Ag,Cu)2S), electrum, and argentian tetrahedrite ((Cu,Fe)12Sb,S13)(Troxel and Morton, 1962, p. 280).

The USGS (MRDS, 2011), lists the following ore minerals: Gold, Electrum, Cerargyrite, Argentite, Proustite, Chalcopyrite, Galena, Alunite, Kaolinite, Adularia, Pyrite, Marcasite, Arsenopyrite. Gangue minerals are quartz and calicite

Areas of intense hydrothermal alteration occur above and peripherally adjacent to some ore zones. Hydrothermal alteration occurs when heated aqueous. solutions rise up through joints. fissures. or fault zones and change minerals and rocks in the process. These altered zones at the Cactus mine aid in identifying ore-bearing structures. Alunite (a hydrous aluminum and potassium sulfate) is the most common mineral within this alteration zone. Kaolinite clay. illite clay, and hematite (iron oxide) also occur within zones of hydrothermal alteration (Burnett and Brady, 1990, p. 86).

Free gold and silver occur as submicroscopic grains and are associated with quartz (silicon dioxide), pyrite (iron oxide). arsenopyrite (iron arsenic sulfide).and iron oxide,. Some ore zones arc quite deep and extend below the deepest exploration holes. All of the gold ore at the mine site occurs in or near a coarse grained rhyolite that forms several intrusive domes. In some areas of the mine. 0.1 ounce of gold ore per ton can be found 20 feet beneath the surface. although no detectable gold may occur at the surface (Burnett and Brady, 1990, p.86.).

METALLURGY

Individual ore bodies were identified and mapped using information derived from a drilling program. Mine development in 1990 was by open pit methods and included successive benches that were placed at 20-foot vertical intervals up the pit wall. The average ore grade at the mine at this time was 0.045 ounce of gold per ton: varying amounts of silver ore also occurred. For example, of the 6,168,000 tons of ore mined from the Shumake pit. the average grade of gold was 0.038 ounce per ton and the average grade of silver was 0.4 ounce per ton (Burnett and Brady, 1990, p.87).

Gold and silver recovery in 1990 was about 71 percent of the total amount of precious metals present in the ore. Mined ore was crushed. mixed with lime and cement. then moved to the cyanide heap leach pile via a conveyor belt that is sprayed with water. The moistened cement binds the fine ore particles and aided percolation of the leaching solution(Burnett and Brady, 1990, p.87).

This map is for my three-part guidebook series “Geology and Mining History of the Mother Lode”

Part I: Mariposa to Jackson
https://www.academia.edu/33103070/MOTHER_LODE_Ia_ROADSIDE_GEOLOGY_AND_MINING_HISTORY_MARIPOSA_TO_JACKSON_TEXT

Part II: Jackson to Grass Valley
https://www.academia.edu/33102851/ROADSIDE_GEOLOGY_AND_MINING_HISTORY_OF_THE_MOTHER_LODE_II_TO_GRASS_VALLEY

Part II: Grass Valley to Taylorsville
https://www.academia.edu/33102890/ROADSIDE_GEOLOGY_AND_MINING_HISTORY_OF_THE_MOTHER_LODE_III_GRASS_VALLEY_TO_WALKER_BASIN

I have produced regional maps for this guidebook series at a scale of 1:50,000. They are designed to be printed on Arch E size poster paper: 36” x 42”.

The maps were created by overlaying the U.S. Geological Survey Digital Geologic Map for California with the ESRI-based U.S. Geological Survey topographic map compilations (2021).

A legend for these maps is accessible at

https://www.academia.edu/60077985/Mother_Lode_Geology_and_Mining_History_Legend_to_Geologic_Maps

The set of regional maps are:

R-01: Mariposa to Moccasin
R-02: Coulterville to Fourth Crossing
R-03: Eagle Shamut to Chilton Peak
R-04: Copperopolis to Plymouth
R-05: Amador to Garden Valley
R-06: Coloma to Nevada City
R-07: Nevada City to La Porte
R-08: Goodyear’s Bar to Quincy
R-09: Blackhawk Creek to Bassetts
R-10: Bassetts to Walker Mine

Avenza.pdf

All the maps in my guidebooks are available as georectified .pdf files. These can be read in the field (without cell phone tower reception) on your smart phone with the Avenza.pdf app. It is downloadable at
https://www.avenza.com/avenza-maps/ 

This application takes my maps and puts a dot on your cell phone or tablet screen to show you where you are as you explore the areas covered by my maps. The free version only lets you load 3 maps a at time. To obtain them as georectified maps, just e mail me at yosoygeologo@gmail.com.

LOCATION: (MRDS, 2011)

Brannigan Gold, Ag  Past Producer
13N 10E Sec. 23 SE, SBM 35.1933 -115.8872
Brannigan Gold Past Producer
13N 10E Sec. 26 SBM 35.1786 -115.8884

Brannigan East Gold. Ag     Past Producer
13N 10E Sec. 26 SBM 35.1825 -115.8856

Brannigan West Gold
13N 10E Sec. 23 SW, SBM 35.194 -115.898

GEOLOGIC DESCRIPTIONS

According to Tucker and Sampson (1943), the vein explored by the Brannigan mine (not on pl. 2) was discovered in 1930. It lies in low gills at the northwest end of the Old Dad Mountains where the country rock is quartzite, shale, and dolomite of the Prospect Mountain Quartzite. The beds trend generally north and dip at low angles east. The vein,1 to 2 feet of quartz, trends N 10° E. and dips 70° W. (Hewett, 1956, p. 122).

Although claims in the Brannigan mine area were located as early as 1905, ore shipments were confined to the period 1928-1935 when the mine was most actively worked. It has yielded several thousand tons of gold ore, carloads of which are said to have averaged as much as $110 per ton (Wright and others, 1953, p. 72). 

The ore bodies occur along fracture zones in quartzite of probable pre-Cambrian age. Most of the gold is in discontinuous quartz veins generally from 3 to 6 feet thick. Some appears to have been mined from thin, bedding-plane seams (Wright and others, 1953, p. 72). 

Th U.S. Bureau of Mines report for the East Mojave Scenic Area (1990, Vol 1,Table 2, p. 138) records this about the Brannigan East mine  :

Bedding plane shears and fracture zones in quartzite and dolomite contain quartz veins and zones of iron oxides. One iron-oxide stained, vuggy quartz vein strikes N. 60° W. dips 39° NE, has blebs of galena, and has minor secondary copper staining. The iron oxides range from brown to pink to purple and have varying amounts of silica; some may be a low grade of jasper (USBOM, 1990, p. 138).

Th U.S. Bureau of Mines report for the East Mojave Scenic Area (1990, Vol 1,Table 2, p. 138) records this about the Brannigan Mine:

Fracture zones in quartzite contain numerous discontinuous quartz veins that are 3 to 6 ft thick (Wright and others, 1953, p. 72). Two mineralized zones are about 1/4 mi apart. The westerly zone strikes about N. 25o 60° E. and dips steeply northwestward; maximum dimension is about 200 ft. The eastern zone trends northwestward and dips moderately to the southwest, although crosscutting shears strike N. 80° E. and dip 40°· 60° NW. Multicolored sandstone also occurs in the area (USBOM, 1990, p. 139).

DEVELOPMENT

During 1938, 1939, and 1940, it yielded 51 tons of ore containing 59 ounces of gold and 20 ounces of silver, which was milled nearby (Hewett, 1956, p. 122).

Two zones about a quarter of a mile apart contain most of the mine workings. The more westerly, or Number 1, workings follow a zone that strikes about N. 35° E. and dips steeply northwestward. Several northeast- trending drift adits have penetrated a segment of the zone no more than 200 feet in maximum dimension. The Number 2 workings consist of three adit levels, driven southeastward within a vertical distance of about 70 feet, that explore a fracture zone that trends northwestward and dips moderately southwest. Most of the ore recovered from this zone has been obtained from winzes and stopes of the upper and middle levels which are about 200 and 50 feet long respectively. The lower level, about 300 feet long, appears to be in barren quartzite. Also on the Brannigan property are several pits from which a small tonnage of variegated lavender, orange and red, fine-grained sandstone has been mined as ornamental stone (Wright and others, 1953, p. 72-73).

Brannigan East Mine

Six adits, the longest is 50 ft, and five prospect pits are on the property. Production is reported with the Brannigan mine (0060710076)…. Seven samples (CRR-42 to 48) ranged from 23 ppb to 8, 750 ppb gold, one had 160 ppm silver, and one sample contained 38.8 ppm scandium. (USBOM, 1990, p. 138),

Brannigan Mine

In the eastern zones, four adits are in a vertical distance of 70 ft; most production was from winzes and stopes from the upper and middle levels which are 50 to 200 ft long, respectively. The lower level extends about 540 ft; two winzes follow structures downward. Four shafts 10 to 35 ft deep and several pits are also in the vicinity. Between 1928 and 1935, several thousand tons of ore were produced that averaged as much as $110 per ton (Wright and others, 1953, p. 72). During 1938, 1939, and 1940, 51 tons of ore mined contained 59 oz gold and 20 oz silver (Hewett, 1956, p. 122) . Also, several pits on the property produced a small tonnage of ornamental sandstone. In the western zone, a 250·ft drift adit has stoping upward; four other adits are each less than 50-ft long; two shallow shafts and several pits are nearby. Ore mined after 1938 averaged 1.16 oz/ton gold and 0.4 oz/ton silver. Eleven 1990 USBM samples (CRR-99, 100, 102 to 110) ranged from 33 to 11,000 ppb gold, and two contained 199 and 299 ppm
Tungsten (USBOM, 1990, p. 139),
.