Masonic District

Past Producer in Mono county in California, United States with commodities Gold, Silver, Copper, Lead, Mercury, Arsenic, Antimony, Bismuth

Sections on this page

Identification information
Geographic coordinates
Site location context
Geographic areas
Public Land Survey System information
Commodities
Materials information
Alteration
Mineral occurrence model information
Host and associated rocks
Nearby scientific data
Ore body information
Controls for ore emplacement
Economic information about the deposit and operations
Mining district
Land status
Bibliographic references
General comments
Reporter information

Geologic information

Identification information

Deposit ID	10310709
Record type	District
Current site name	Masonic District
Alternate or previous names	Success, Chemung, Gold Fund, Home View, Lakeview (Lake View), Maybell, Melor, Perini (Perrini), Pittsburg Liberty, Red Rock, Rough-and-Ready, Serita (Sarita), Valley View, New York, Jump-Up-Joe, Lost Horse

Comments on the site identification

The Masonic District comprises numerous small mines and prospects spread over a mountainous area northeast of Bridgeport in the Basin and Range Province.

Geographic coordinates

Geographic coordinates:	-119.12444, 38.3575 (WGS84)
Elevation	2620
Location accuracy	100(meters)
Relative position	The approximate center of the Masonic District is at the top of New York Hill, which is about 12 miles north-northwest of the historic gold mining town of Bodie and 11 miles northeast of Bridgeport.

Site location context

Political divisions (FIPS codes)

Mono(county)

California(state)

United States(country)

North America(continent)

Land(continent)

USGS map quadrangles

Dome Hill(quadrangle 1:24,000 scale)

Bridgeport(quadrangle 1:100,000 scale)

Walker Lake(quadrangle 1:250,000 scale)

Hydrologic units (watersheds)

East Walker(hydrologic unit)

Walker(hydrologic accounting unit)

Central Lahontan(hydrologic subregion)

Great Basin(hydrologic region)

Federal lands

Humboldt-Toiyabe National Forest(National Forest)

National Forest FS(Type of land area)

FS(Federal land areas administered by FS)

Geographic areas

Country	State	County
United States	California	Mono

Public Land Survey System information

Meridian	Township	Range	Section	Fraction	State
Mount Diablo	006N	026E	10, 14, 15, 16, 17, 18, 20, 21, 22, 23, 24, 27, 28, 29, 30		California

Comments on the location information

The location selected for latitude and longitude is the top of New York Hill, elevation 8612 feet (2625 m), approx. 8.9 air miles (14.3 km) N39.3?E of Bridgeport, CA. New York Hill is located at the approximate center of the Masonic Mining District. New York Hill can be reached by traveling from Bridgeport, CA, 3.8 miles (6 km) north on State Hwy 182 to the junction of Masonic Road (unpaved), then 7 miles (11.3 km) east on Masonic Road to New York Hill. The Success Mine, located near the west margin of the district, is approx. 4.1 (6.6 km) east of the junction of Hwy 182 and Masonic Road. New York Hill is 8.98 air miles (14.45 km) N39.28?E of Bridgeport, CA, and 11.99 air miles (19.30 km) N31.01?W of the historic townsite of Bodie, CA. The Masonic District can also be reached by traveling approx. 16 miles (25.7 km) northwest from Bodie on Bodie Masonic Road (unpaved). Unpaved roads in the region are closed during winter and can be impassible during inclement weather.

Commodities

Commodity	Importance
Gold	Primary
Silver	Primary
Copper	Tertiary
Lead	Tertiary
Mercury	Tertiary
Arsenic Critical	Tertiary
Antimony Critical	Tertiary
Bismuth Critical	Tertiary

Comments on the commodity information

Commodity Info: Ore Grade:
Historic mining: 0.15-1.9 troy ounces/short ton gold.
Pittsburgh Liberty Mine: 0.97 troy ounces/short ton gold;
Serita (Sarita) Mine: 0.15-1.9 troy ounces/short ton gold.

Modern exploration (Sarita/Masonic Project): 0.09-0.15 troy ounces/short ton gold; 0.3-6.0 troy ounces/short ton silver.
Ore Materials: Native gold, gold tellurides, galena, argentite, bornite, chalcopyrite, famatinite or enargite, malachite, chrysocolla, stibnite, bismuthite, cinnabar, tellurides, selenides, barite, unidentified fine-grained black mineral high in silver content.
Gangue Materials: Chalcedony, quartz, opal, hematite, limonite, gypsum, barite, jarosite, chlorite, epidote, albite, montmorillonite, illite, sericite, adularia, calcite, native sulfur

Materials information

Materials	Type of material
Gold	Ore
Telluride	Ore
Galena	Ore
Argentite	Ore
Bornite	Ore
Chalcopyrite	Ore
Famatinite	Ore
Enargite	Ore
Malachite	Ore
Chrysocolla	Ore
Stibnite	Ore
Cinnabar	Ore
Telluride	Ore
Barite	Ore
Chalcedony	Gangue
Quartz	Gangue
Opal	Gangue
Hematite	Gangue
Limonite	Gangue
Gypsum	Gangue
Barite	Gangue
Jarosite	Gangue
Chlorite	Gangue
Epidote	Gangue
Albite	Gangue
Montmorillonite	Gangue
Illite	Gangue
Sericite	Gangue
Adularia	Gangue
Calcite	Gangue
Sulfur	Gangue

Alteration

(Local) Silicic; quartz, opal, chalcedony
Advanced Argillic; kaolinite, alunite
Propylitic;

Silicification is of several varieties, including, in probable temporal order, from early to late: 1) gray opal flooding; 2) dense, fine, quartz-alunite with sporadic crystalline alunite in pheonocryst sites; 3) a fine chalcedony-opal flooding; and 4) black chalcedony-opal-microcrystalline pyrite veins; fine chalcedony-opal flooding into the hanging wall on the southeast of the Chemung structure.

The alteration sequence as reported by (Johnson, 1951) (from oldest to youngest):
1. Sericitic alteration, which is most abundant in the granodiorite;
2. Quartz-alunite-kaolinite alteration with diaspore in the outer portion of this zone;
3. Increase in silica by deposition of silica or leaching of other constituents, or both.

Mineral occurrence model information

Model code	154
USGS model code	25e
Deposit model name	Epithermal quartz-alunite Au
Mark3 model number	38

Host and associated rocks

Host or associated

Host

Rock type

Volcanic Rock (Aphanitic) > Intermediate Volcanic Rock > Andesite

Rock unit name

Red Wash Volcanics

Stratigraphic age (youngest)	Middle Miocene
Chronological age	15

Host or associated

Host

Rock type

Volcanic Rock (Aphanitic) > Mafic Volcanic Rock > Basalt

Rock unit name

Red Wash Volcanics

Stratigraphic age (youngest)	Middle Miocene
Chronological age	15

Host or associated

Host

Rock type

Plutonic Rock > Granitoid > Granite

Rock unit name

Masonic Mountain Granodiorite

Stratigraphic age (youngest)	Cretaceous

Host or associated Associated

Rock type Metamorphic Rock

Stratigraphic age (youngest) Cretaceous
Host or associated Associated

Rock type Volcanic Rock (Aphanitic)

Stratigraphic age (youngest) Pliocene

Stratigraphic age (oldest) Miocene

Nearby scientific data

(1)	-119.12444, 38.3575	ListMap

Economic information

Ore body information

General form Lenticular masses, zones or "ledges" ("ledges" follows the usage of Ransome, 1909, for ore bodies at Goldfield, Nevada)

General form	Lenticular masses, zones or "ledges" ("ledges" follows the usage of Ransome, 1909, for ore bodies at Goldfield, Nevada)

Controls for ore emplacement

The principal ore controls include temperature, pressure, faulting, and lithology (Red Wash Volcanics and granodiorite). Where the volcanics and granodiorite are in depositional contact, the volcanics are more intensely altered and mineralized. At the Serita Mine, the ore occurs in steeply dipping or vertical zones that extend upward from the basement contact. The mineralized "ledges" are fault-controlled and occur along faults and in association with subsidiary faults oriented 90? or 45? to the strike of the ledges. At the Chemung Mine, highest ore grades occur at intersections of cross faults and the main veins ("ledges"). At the Perini and "Goldfound" (Gold Fund) mines, stoping is most prevalent on cross faults in the "ledges".

The hard silicified "ledges" formed in association with faulting. Subsequent faulting shattered the ledges, providing permeable passageways for subsequent gold-bearing hydrothermal fluids. Gouge zones are present along the margins of the ledges. At the Serita Mine, silicification is areal in extent as compared to silicified linear "ledges" in other parts of the district. All of the productive mines in the district have been in silicified zones or ledges, but not all such zones or ledges have been productive.

The northeast trending fault zone north of Masonic Mountain is a likely candidate for the deeper portion of the hydrothermal system associated with gold mineralization in the Masonic District.

Comments on the geologic information

Regional Geology and deposit overview

The geology is characterized by Tertiary calc-alkaline volcanism overlying pre-Tertiary crystalline basement rocks in a structural basin. There are two prominent tectonic features in the region: 1) the Fletcher-Coal Valley Basin, developed between ~13 Ma and the present (Gilbert and Reynolds, 1973, cited in King and others, 1996, p. 150), is bounded by northeast-trending faults on the southern margin and northwest-trending faults on the west and east margins; 2) a northeast-trending arch along which are aligned the Bodie, Aurora, and Borealis mining districts. The Masonic District, located 12 miles (19 km) northwest of the Bodie District, appears to be located structurally high on the north flank of this arch.

Regional stratigraphic studies suggest the Fletcher-Coal Valley Basin area, including what is now the Masonic district, received from 1000 to over 3000 feet of andesite flows, tuffs, and lahars in the early Miocene. Later Miocene and early Pliocene tuffaceous sediments added an additional 1000 to 3000 feet. The andesite tuff-andesite porphyry-andesite lahar sequence exposed on Chemung Hill is typical of the early Miocene, and the sequence is offset across the northeasterly-trending Chemung Hill structure.

Northwest tilting at Masonic was most likely concurrent with the latter stages of tuffaceous deposition, and prior to mineralization. At Chemung Hill, movement along the northeast structure post-dated tilting and possibly erosion of much of the tuffaceous section, and subsequent epithermal fluids, associated with precious metals mineralization, vented onto an erosional unconformity. In the Masonic District, initial geothermal activity began at ~13 Ma (King and others, 1996). The fluids appear to have vented onto basal tuffaceous sediments or, if pre-mineral erosion was severe enough, perhaps onto a paleosurface with exposed, northwest-dipping Miocene andesites. In either case, that paleosurface has been eroded from the Chemung Hill area, exposing what is interpreted as the structurally-controlled "feeders" to vents of a fossil epithermal system. Opaline textures and lack of banding in the quartz veins is interpreted to indicate that the paleosurface was less than 1000 feet above the present surface of Chemung Hill.

The presence of crystalline alunite in silica, and narrow kaolin selvages, combined with an observed lack of sericite in wall rocks, indicate Chemung Hill (and three other areas described in Strachan's report) is an acid sulfate epithermal system (Heald and others, 1987, p. 8; cited in Strachan, 1987, p. 5).

Stratigraphy, its relation to mineralized structures, and the observed style of alteration suggest no epithermal vent-related, or paleosurface-related, disseminated gold mineralization is preserved at Chemung Hill.

Bulk-tonnage drill targets of possible economic significance at Chemung Hill are vein and breccia vein stockworks in silicified wall rocks, most likely the andesitic tuff breccia of the southeast hanging wall. Also, silica-flooded zones between -parallel veins of the Chemung structure may not have been conclusively tested by Santa Fe.
DISTRICT GEOLOGY (from Chesterman and others, 1986; Clark, 1979; Eakle and McLaughlin, 1917; Johnson, 1951; Sampson and Tucker, 1940; Strachan, 1987)

The district is underlain by crystalline basement including pre-Cretaceous(?) granodiorite and lesser quartz monzonite and granite, and by pre-Cretaceous gneiss and schist. These crystalline rocks are overlain by a sequence of Tertiary volcano-stratigraphic rocks (lava flows and pyroclastics) varying in composition from dacite to andesite and basalt, with andesite being most abundant. Johnson (1951) identified three distinct volcanic cycles represented in the volcanic rocks in the district. The crystalline basement and volcanic rocks are intruded locally by plugs and dome-like intrusions of andesite and basalt.

Volcanism commenced in the Bodie Hills ~17 Ma ago with eruption of calc-alkaline andesite, dacite, and rhyodacite onto a peneplained surface. Initial geothermal activity followed at ~13 Ma at Masonic in the northern present-day Bodie Hills (King and others, 1996).

Two prominent tectonic features in the region are: 1) the Fletcher-Coal Valley Basin, developed between ~13 Ma and the present (Gilbert and Reynolds, 1973, cited in King and others, 1996, p. 150), which is bounded by northeast-trending faults on the southern margin and northwest-trending faults on the west and east margins; and 2) a northeast-trending arch along which are aligned the Bodie, Aurora, and Borealis mining districts. The Masonic District, located 12 miles (19 km) northwest of the Bodie District, appears to be located structurally high on the north flank of this arch.

In the Masonic District, mineralization began after widespread propylitic alteration of the oldest Tertiary volcanics (Red Wash Volcanics of Johnson, 1951) and ended prior to onset of several periods of younger volcanic activity. Ore bodies occur only in the oldest Tertiary rocks and in the pre-Tertiary crystalline rocks; younger volcanics are only locally altered and do not contain sulfide mineralization.

The ore deposits are thick, silicified, northwest- to northeast-striking zones and veins, or "ledges" (Johnson, 1951) in porphyritic, coarse-grained granitic rocks, and in the overlying lowermost Tertiary volcanic sequence. The ore consists of fine free gold in brecciated and re-cemented chert, quartz, and chalcedony. Milling ore typically contains less than one troy ounce of gold per short ton, but appreciable high-grade has been recovered. None of the deposits has been developed to depths of more than a few hundred feet.
Crystalline Basement (Chesterman and others, 1986; Johnson, 1951)

Pre-Cretaceous gneiss and schist crop out at Masonic Mountain (Koenig, 1963, cited in Chesterman and others, 1986). A body of pre-Cretaceous (age uncertain) granite also crops out at Masonic Mountain (Koenig, 1963, cited in Chesterman and others, 1986).

According to Johnson (1951), the pre-Tertiary crystalline rocks are quartz-feldspar-mica schists intruded by granodiorite and an isolated granitic stock. The oldest volcanic rocks, Red Wash Volcanics, unconformably overlie locally altered and mineralized schist (amphibolite-grade locally) and the Masonic Mountain granodiorite, which is exposed over 6 square miles (15.5 square kilometers) of the central and eastern portions of the district. The Masonic Mountain granodiorite (locally quartz monzonite) is a medium- to coarse-grained, porphyritic, biotite granodiorite with large, tabular orthoclase and microcline phenocrysts up to 5 cm (2 inches) in length that comprise up to 5%-20% of the rock by volume. Aplite, pegmatite, and quartz veins are abundant in the granodiorite. The Jump-Up-Joe Mine northeast of Masonic Mountain is the only mine in the Masonic Granodiorite that is not associated with breccia dikes or extrusives of the Red Wash Volcanics.

Another prominent igneous unit that underlies the area along the East Walker River is the Murphy Creek biotite granite to quartz monzonite, a homogeneous, medium-grained rock containing quartz, potash feldspar, minor plagioclase, and sparse biotite.

Tertiary Stratigraphy (Johnson, 1951; Strachan, 1987)

Johnson (1951) identified three distinct volcanic cycles represented in the volcanic rocks in the district (from youngest to oldest):
1) Dacite welded tuff (Unit 1), pumiceous tuff, and thin dacite and andesite flows; Pliocene: unmineralized. Units 1 and 2 are separated by a disconformity.
2) Masonic Gulch Volcanics (Unit 2): andesite flows and agglomerate (ignimbrites and welded tuffs), dacite and basalt flows, andesitic and basaltic intrusives; Pliocene; unmineralized. These volcanic units are thin or absent in the Dome Hill area. Units 2 and 3 are separated by an unconformity.
3) Red Wash Volcanics (Unit 3): propylitic andesite flows and breccia (hornblende andesite), and basalt; Miocene; locally hydrothermally altered and mineralized. Johnson was uncertain if the propylitic alteration is due to deuteric alteration or if it coincides with the mineralizing hydrothermal event. This unit crops out from the Perini Mine northward in the eastern portion of the district, and in the area west to north of Masonic Mountain, where the unit is faulted down against the schist basement. The Red Wash Volcanics are the host rocks for most of the ore bodies. The groundmass is partly recrystallized, and ferromagnesian minerals have been completely altered either to hematite or antigorite pseudomorphs or to aggregates of chlorite, carbonate, and epidote. Feldspars have been largely altered to carbonate or to epidote and clinozoisite. Albite is a common mineral of some propylitized lavas. Accessory minerals include apatite, quartz, magnetite, pyrite, sphene, leucoxene, and sericite. West of Masonic Mountain, the volcanics are highly silicified. The Red Wash Volcanics are 2000-5000 feet (610-762 meters) thick, and unconformably overlie schist and the Masonic Mountain granodiorite.
Tertiary Intrusive Rocks (Johnson, 1951)

Plugs and dome-like intrusions of andesite or basalt cut all rock types except the dacite welded tuff unit. These intrusions are generally 200-300 feet (61-91 meters) in diameter; those north of the Serita Mine are larger.

All of the above units are overlain locally by pediment gravels, alluvium, and slope wash deposits.

Strachan (June 1987) identified three volcano-stratigraphic units that crop out in the Chemung Mine area in the southwest portion of the Masonic District. These units (from youngest to oldest) include:
1) the uppermost unit, an andesite lahar, consists of clasts of pebble- to boulder-sized, subrounded, multi-lithologic andesites in an andesitic matrix.
2) the middle unit, porphyritic andesite, consists of 15% to 25% hornblende, biotite, and feldspar phenocrysts; feldspars with a platy crystal habit; with sub-parallel alignment of phenocrysts, that appear to be aligned parallel to original bedding. This unit is interpreted to be a series of flows, with interbedded tuffaceous sediments.
3) the lowermost unit, andesite tuff breccia, consists of monolithic clasts of altered fine andesite porphyry with randomly oriented phenocrysts in a reddish brown matrix of rock flour, deuteric silica, and disseminated fine hematite. Clasts have rough (but not elongate) margins and are normally less than 4 cm (1.6 in) across. This unit is believed to be a stratiform, proximal, talus deposit with original undulatory contacts offset by younger faults.

This MRDS reporter does not know if the three "volcano-stratigraphic units" of Strachan (1987) are equivalent to the three "volcanic cycles" described by Johnson (1951).

Structure (Strachan, 1987)

The dominant structure of Chemung Hill is a series of northeast-striking, near vertical veins and fractures, of which the West, Main, and East veins are most prominent. Santa Fe (in Strachan, 1987) reported a distance of 40 feet (12.2 m) between the West and East veins. Thin quartz veins that strike north-northwest in outcrop are interpreted to be subsidiary to, and co-genetic with, the three prominent vein systems.

Bedding, as reflected by phenocrysts alignment in the middle porphyritic andesite unit, strikes N10?W to N12?E, and dips 45? to 50? to the west. Post-mineralization faults that offset the veins of Chemung Hill strike north and dip 75? to 84? to the west.
Alteration (Strachan, 1987; Johnson, 1951)

As reported by Strachan (1987), the Tertiary volcanics in the Chemung Hill area have undergone silicic, argillic, and propylitic alteration. Silicic alteration observed in outcrop and in mine dumps, affects andesite porphyry (middle unit) and andesite tuff breccia (lowest unit), but not the andesite lahar (upper unit). Silicification is of several varieties, including, in probable temporal order, from early to late: 1) gray opal flooding; 2) dense, fine, quartz-alunite with sporadic crystalline alunite in pheonocryst sites; 3) a fine chalcedony-opal flooding; and 4) black chalcedony-opal-microcrystalline pyrite veins. All four silicic types are concentrated along the main northeast axial structure of Chemung Hill, with additional fine chalcedony-opal flooding into the hanging wall on the southeast. There is little or no disruption of primary textures by silicification in the hanging wall, other than some late quartz veining.

Outcrops or surface workings in rocks with argillic alteration are extremely limited on Chemung Hill, due to argillic alteration occurring as narrow, limited selvages. Propylitized andesites occur in close proximity to outcrops of silicic rock, including poorly mineralized opaline rock, and relatively well-mineralized brecciated silicic rock.

At the Serita and Pittsburg Liberty mines, Johnson (1951) reports that the highly altered rocks are composed almost entirely of quartz with minor leucoxene and pyrite. Chalcedony veinlets cut the quartz, and gold is associated mainly with the chalcedonic silica in veinlets and cavity fillings.

The alteration sequence as reported by (Johnson, 1951) (from oldest to youngest):
1. Sericitic alteration, which is most abundant in the granodiorite;
2. Quartz-alunite-kaolinite alteration with diaspore in the outer portion of this zone;
3. Increase in silica by deposition of silica or leaching of other constituents, or both.
Mineralization (Johnson, 1951)

Precious-metals mineralization in the Masonic District began after widespread propylitic alteration of the oldest Tertiary units (oldest volcanic cycle) had occurred, and was completed before the start of a second (younger) cycle of volcanic activity. Ore bodies occur only in the oldest Tertiary volcanic rocks and in the pre-Tertiary crystalline rocks. The younger Tertiary volcanic rocks of the second and third volcanic cycles are only locally altered and have no associated sulfide mineralization.

Mineralization occurs in the form of "ledges" or lenticular masses of quartz-alunite rock. The term "ledges" used by Johnson (1951) follow the usage of Ransome (1909) [cited in Johnson (1951)] for ore bodies at Goldfield, Nevada. Ore deposition followed formation and brecciation of these ledges. The associated alteration consists of an innermost zone of quartz and alunite or quartz alone; a middle zone of quartz, alunite, kaolin, and diaspore; and an outer zone of sericitized and kaolinized rock or granodiorite.

Quartz, chalcedony, pyrite, famatinite or enargite, and, finally, gold were deposited from hydrothermal solutions that flowed along fractures in the permeable ledges. The solutions probably originated at depth along one or more fault zones.

Amorphous sulfur occurs at the Success Mine in the southwest portion of the district.

Gold occurrence:
a. At the Chemung and Success mines, gold occurs as fine particles in milky quartz veinlets.
b. In the northern part of the district, gold occurs with chalcedony in thin seams or as bands in vugs. Gold commonly occurs in the youngest (last) chalcedonic band to be deposited. The gold in finely disseminated and appears as purplish clouds in the chalcedony.
c. Nearly all of the gold is native, but tellurides have been reported.
Galena occurs in quartz veins in granodiorite at the Sunday prospect immediately east of the Pittsburg Liberty Mine on the opposite side of Masonic Gulch. Argentite, present in ore from the Sunday claim, occurs with and replacing galena.
Bornite occurs with chalcopyrite in a copper prospect vein southeast of the Success Mine. The vein is in schist and is probably related to a mineralization event than is older than the gold mineralization in the Masonic District.
Chalcopyrite occurs with bornite at the above-mentioned prospect, and as small grains at the True Friend Mine.
Famatinite or enargite is common at the Serita and Pittsburg Liberty mines; these minerals gave a positive test for both arsenic and antimony.
Chalcedony occurs as banded cavity filling, and is abundant at the Serita and Pittsburg Liberty mines. Thin sections reveal bands composed of chalcedony and quartz.
Opal occurs as wallrock at the Chemung Mine and locally elsewhere in the altered rocks.
Hematite occurs as earthy red coatings or in cavities.
Limonite occurs as thin coatings and is pseudomorphous after pyrite.
Malachite occurs at the copper prospect southeast of the Success Mine.
Chrysocolla occurs at the copper prospect southeast of the Success Mine and in at the True Friend Mine.
Scorodite(?) occurs in vugs at the Pittsburg Liberty Mine.
Gypsum occurs in cavities at the Serita Mine.
Melanterite occurs as a bluish-green efflorescence on walls of old workings; it loses color on exposure to light.
Jarosite occurs as small, brown crystals associated with limonite in cavities in "ledge" matter.
Other reported minerals include stibnite, bismuthite, cinnabar, tellurides, selenides, and barite.
A fine-grained black mineral high in silver content occurs north of the Chemung Mine.
Mineralization (Strachan, 1987) -Tertiary Volcanics, Chemung Hill

Goethite, hematite, and Jarosite on fractures, and microcrystalline pyrite in black chalcedony-opal veins are common at Chemung Hill, but not abundant; no other sulfide minerals or oxides after sulfide minerals were observed.
Adularia is absent in this system.
Paragenesis (Johnson, 1951)

Quartz ___________________________________
Chalcedony ________________________
Pyrite in banded quartz veins ___________
Gold _ _ _ _ _ _ _ _ _ _ _ ____________ _

(Most of the gold was deposited late in chalcedonic silica lining vugs or in the center of vuggy veinlets.)

Significant Local Structures (Johnson, 1951)

Common structures associated with the gold mineralization include comb structures, open cavities, cavities filled with banded chalcedony, crustification banding, and open fractures; replacement is a minor component of mineralization in the district.

Ore Controls (Johnson, 1951)

The northeast trending fault zone north of Masonic Mountain is a likely candidate for the deeper portion of the hydrothermal system associated with gold mineralization in the Masonic District.

The principal ore controls include temperature, pressure, faulting, and lithology (Red Wash Volcanics and granodiorite). Where the volcanics and granodiorite are in depositional contact, the volcanics are more intensely altered and mineralized. At the Serita Mine, the ore occurs in steeply dipping or vertical zones that extend upward from the basement contact. The mineralized "ledges" are fault-controlled and occur along faults and in association with subsidiary faults oriented 90? or 45? to the strike of the ledges. At the Chemung Mine, highest ore grades occur at intersections of cross faults and the main veins ("ledges"). At the Perini and "Goldfound" (Gold Fund) mines, stoping is most prevalent on cross faults in the "ledges".

The hard silicified "ledges" formed in association with faulting. Subsequent faulting shattered the ledges, providing permeable passageways for subsequent gold-bearing hydrothermal fluids. Gouge zones are present along the margins of the ledges. At the Serita Mine, silicification is areal in extent as compared to silicified linear "ledges" in other parts of the district. All of the productive mines in the district have been in silicified zones or ledges, but not all such zones or ledges have been productive.
The northeast trending fault zone north of Masonic Mountain is a likely candidate for the deeper portion of the hydrothermal system associated with gold mineralization in the Masonic District.

Geochemistry (Strachan, 1987)

Underground sampling represented on Santa Fe Mineral's cross-sections includes results from two crosscuts, the first between the West and Main veins, and the second between the Main and East veins, respectively: 25 feet (7.6 m) of 0.384 troy ounces gold/short ton, and 40 feet (12.2 m) of 0.081 troy ounces gold/short ton.

Underground sampling by Kennecott consisted of 18 samples that yielded the following:
Element Mean Range
Au (ppb) 478 15 to 6050
Ag (ppm) 21.9 2.2 to 65.0
As (ppm) 55 11 to 280
Hg (ppb) 24,792 7000 to 71,000

Surface sampling by Kennecott consisted of 89 samples that yielded the following:
Element Mean Range
Au (ppb) 284 5 to 2500
Ag (ppm) 19.2 0.9 to 150
As (ppm) 108 7 to 790
Sb (ppm) 62 3.2 to 950
Hg (ppb) 20,418 1500 to 120,000

Metallurgy

Bottle cyanide agitation test of Chemung ore, by Legend Metallurgical Laboratory, Reno, NV (1988):
Gold extraction, ppm: 1.57
troy oz/ton: 0.137
% of total: 89.5
Silver extraction, ppm: 4.05
troy oz/ton: 0.35
% of total: 84.2
Tail assay
troy oz Au/ton: 0.016
troy oz Ag/ton: 0.42
Calculated head
troy oz Au/ton: 0.153
troy oz Ag/ton: 0.77
Head assay
troy oz Au/ton: 0.137
troy oz Ag/ton: 0.73
Deposit Geologic Environment - SUMMARY

The Masonic District is characterized by Tertiary calc-alkaline volcanism occurring in a back-arc spreading environment. Pre-Cretaceous crystalline basement includes quartz-feldspar-mica schists and hornfels (amphibolite grade locally) intruded by pre-Tertiary biotite granodiorite (locally quartz monzonite) and lesser granite.

Regional stratigraphic studies suggest the Fletcher Basin area, including what is now the Masonic district, received from 1000 to over 3000 feet of andesite flows, tuffs, and lahars in the early Miocene. Later Miocene and early Pliocene tuffaceous sediments added an additional 1000 to 3000 feet. The andesite tuff-andesite porphyry-andesite lahar sequence exposed on Chemung Hill is typical of the early Miocene, and the sequence is offset across the northeasterly-trending Chemung Hill structure.

Northwest tilting at Masonic was most likely concurrent with the latter stages of tuffaceous deposition, and prior to mineralization. At Chemung Hill, movement along the northeast structure post-dated tilting and possibly erosion of much of the tuffaceous section, and subsequent epithermal fluids, associated with precious metals mineralization, vented onto an erosional unconformity. The fluids appear to have vented onto basal tuffaceous sediments or, if pre-mineral erosion was severe enough, perhaps onto a paleosurface with exposed, northwest-dipping Miocene andesites. In either case, that paleosurface has been eroded from the Chemung Hill area, exposing what is interpreted as the structurally-controlled "feeders" to vents of a fossil epithermal system. Opaline textures and lack of banding in the quartz veins is interpreted to indicate that the paleosurface was less than 1000 feet above the present surface of Chemung Hill.

Depth of mineralization:
None of the deposits has been developed to depths of more than a few hundred feet.

Economic information about the deposit and operations

Operation type	Surface-Underground
Development status	Past Producer
Commodity type	Metallic
Deposit size	Small
Significant	Yes
Discovery year	1902

Mining district

District name	Masonic District

Land status

Ownership category	National Forest
Area name	USFS Toiyabe National Forest

Comments on the workings information

Workings Type: Underground and open-pit. Numerous mine and prospect symbols representing adits, shafts, and open cuts dot the area of the district.

From Strachan (1987):

Workings at Chemung Hill include numerous prospect pits, trenches, adits, small shallow shafts, and open stopes, most of which are concentrated on the lower southwest slopes of Chemung Hill near the old mill ruins. Four of the largest dumps on Chemung Hill may total 1500 short tons.

Cross-sections in Santa Fe Mineral's 1984 report indicate workings on three parallel, vertical veins (West, Main, East) beneath the northeasterly axis of Chemung Hill. Santa Fe did not supply information as to the extent of the underground workings, other than that shown on Santa Fe's cross-sections. Deepest stopes were apparently at the 165-foot (50.3-meter) level [8025 feet (2446 m) elevation]; a shaft apparently extended below the 8000-foot (2438.4 m) level.

Comments on other economic factors

Production: estimate 3.02 metric tons produced.
Reserves: estimate 4.7 metric tons reserves.

Ore Grade:

Historic mining: 0.15-1.9 troy ounces/short ton gold.
Pittsburgh Liberty Mine: 0.97 troy ounces/short ton gold;
Serita (Sarita) Mine: 0.15-1.9 troy ounces/short ton gold.

Modern exploration (Sarita/Masonic Project): 0.09-0.15 troy ounces/short ton gold; 0.3-6.0 troy ounces/short ton silver.

Recovery:

94% gold recovery during metallurgical testing for modern mining (conventional cyanide process).

Comments on development

OVERVIEW

The Masonic Mining District is located, for the most part, in northeastern Mono County, CA, and extends eastward into the State of Nevada. The district, located in the northern part of the present-day Bodie Hills, was prospected during and after the Comstock rush of the early 1860s, but valuable ore was not discovered until August 1902. This discovery developed into the Pittsburg Liberty Mine. No considerable production occurred until 1907, when 17 short tons of ore were shipped from the Pittsburg Liberty to the Selby smelter near San Francisco.

The chief period of production in the Masonic District was 1907-1910. Some activity continued through the 1930s, and the Chemung Mine was intermittently worked as late as the late 1960s. By 1970, the district had produced an estimated 63,000 troy ounces (1.96 metric tons) to 97,000 troy ounces (3.02 metric tons) gold based on reported dollar value of production of approximately $1.3 million (Clark, 1979) and $2.0 million (Johnson, 1951), and an average gold value of $20.67 per troy ounce gold during the peak production period for the district.

Production and Reserve Size: Estimated 7.7 metric tons gold total (3.02 metric tons produced; estimate 4.7 metric tons reserve).
HISTORIC MINING

In the summer of 1860, the Masonic District was first prospected and promising gold ore was discovered by prospectors from the mines at Monoville, California. The new district was named Masonic because a majority of the workers were Masons. During the same period, rich gold strikes at Aurora, Nevada, and Bodie, California, created a boom, and attention was diverted from Masonic.

In 1900, Joseph Green, a 16-year-old boy from Bodie, found rich gold samples in Masonic Gulch and staked his claim as the Jump Up Joe Mine. Green sold the mine to Bodie miner, Warren Loose, in 1901.

On July 4, 1902, John Stuart Phillips, Caleb Dorsey, and John M. Bryan located a rich quartz ledge which developed into the Pittsburg Liberty Mine. The ore reportedly assayed at $35.00 (1.69 troy ounces gold/short ton equivalent) to $800.00 per ton (38.7 troy ounces gold/ton equivalent; based on a gold value of $20.67 per ounce; dollar value presumably includes gold and silver).

The Masonic District covered an area of about 6 (9.7 km) by 12 miles (19.3 km). Early successful mines included the Pittsburg Liberty, Jump-Up-Joe, Serita (aka Sarita), Myrtle & Julia, True Friend, New York, and Red Rock. In 1907, the Pittsburg Liberty Mine opened a 10-stamp, 30-35-ton per day mill, with 50 men on payroll. On October 1, 1908, a cyanide plant was put into operation, which worked the tailings. Total production reportedly amounted to $700,000 (33,866 troy ounces gold/ton equivalent).

In 1904, the first real town in the district, Lorena, was established at the south end of Masonic Gulch. Offices of the Pittsburg Liberty Mine and the Masonic Mountain Gold Mining Company were located in Lorena, and the first post office in the region was opened in Lorena in 1905. A settlement abut a half mile north of Lorena was called Middle Town, and another half mile farther north was named Caliveda, later known as Lower Town; Lorena was renamed Upper Town. All three eventually co-existed as "Masonic". Masonic grew to about 1000 residents.

In 1909, ore at what became the Chemung Mine was located 3 miles (4.8 km) west of Masonic Gulch, at the southwest end of the district, but the Pittsburg Liberty and Jump-Up-Joe mines remained the main producers. The district began its decline in 1911 as rich pockets were found and exhausted in a relatively short period of time. The only school in Masonic opened in 1911 and closed in 1929.

Peak mining activity in the Masonic District occurred between 1906 and 1911. In January 1912, a strike was made at the Serita Mine. During 1920, A. G. Cook and Eastern Associates operated the Chemung Mine, which produced both low- and high-grade ore. The closest operating mill was in Bodie, and the road to Bodie became difficult to use. Elton Heinemeyer worked the Chemung during the 1950s and 60s. Between 1920 and 1929, new ore was developed sporadically in the area of Masonic Gulch. In 1929, the Serita Mine reopened for a short period. By the mid 1950s no one lived in Masonic.

Historic mines in the district include the Pittsburg Liberty, Serita (Sarita), Red Rock, Chemung, Home View, Lakeview, Valley View, Success, Maybell, Perrini, Melor, Rough-and-Ready, New York, Jump-Up-Joe, Lost Horse, Gold Fund, and True Friend.
HISTORIC MINING (continued)

Pittsburg Liberty Mine; T6N, R26E, Secs. 15, 16:
The Pittsburg Liberty was located in August 1902 by J. M. Bryan, Kaleb Dorsey, and J. S. Phillips. Their discovery became the Pittsburg Liberty Mine. No considerable production occurred until 1907, when 17 short tons of ore were shipped from the Pittsburg Liberty to the Selby smelter near San Francisco. The ore netted $1040.00 per short ton (50.3 troy ounces gold per ton equivalent; undoubtedly concentrates), the product of five men's work during the summer, and at a total depth of 15 feet. The Pittsburg Liberty operated until 1910 with reported production of $600,000 to $700,000 (29,028 to 33,866 troy ounces gold equivalent at a price of $20.67 per troy ounce gold; the ore also contained silver, which accounts for an unknown portion of the production).
Early development at the Pittsburg Liberty consisted of a 172-foot deep shaft and two tunnels cutting veins at a depth of 271 feet and 413 feet. The mine produced from stopes that developed several quartz veins or silicified zones in granite, most dipping from 70? to 90?. A map of the workings indicates 5 quartz veins striking N25?W and dipping steeply to the east. One zone changes from an easterly to a westerly dip along its trend. The ore averaged about $20.00 per ton (approx. 0.97 troy ounces gold per ton at $20.67 per ounce gold). The greatest depth stoped below the outcrops was about 150 feet. The aggregate of underground workings totals approximately 6000 feet. The property was equipped with a 60-ton cyanide plant.

Serita (Sarita) Mine; T6N R26E, Sec 16, 21:
The Serita Mine is located approximately 0.5 mile (0.8 km) southwest of the Pittsburg Liberty. The ore, as seen in shallow surface cuts, is porous chert and chalcedony accompanied by breccia similar to Pittsburg Liberty ore (Eakle and McLaughlin, 1919). The ore carried free gold from $3.00 to $40.00 per short ton (0.15 to 1.9 troy ounces gold per short ton). Its early development consisted of a 218-foot vertical shaft with crosscuts on the 100-foot level. The property was reopened in 1929 and the 50-ton cyanide plant rehabilitated. Reported production from the Serita totaled $60,000 (Clark, 1979) and $500,000 (Johnson, 1951).

Chemung Mine; T6N, R26E, Sec 20:
The Chemung Mine, located about 2.5 miles (4 km) southwest of the Pittsburg Liberty Mine, reportedly produced $60,000 (Clark, 1979). Although activity in the Masonic district declined after 1920, the Chemung and Serita mines produced sporadically from 1920 to 1930. After WW II, a 75-ton mill and cyanide plant was built at the Chemung Mine to mill ore from dumps at the Lakeview and Pittsburg Liberty mines, and from underground workings at the Serita Mine.
Modern Exploration for Bulk-mineable Deposits

Interest in the Masonic District was rekindled with the advent of bulk mining (cyanide heap leaching) in the 1970s and early 1980s. Since the early 1980s several companies have conducted exploration in the southwest portion of the district along a southwesterly trend that includes, from northeast to southwest, the Serita (Sarita) Mine, Red Rock Mine, and Chemung Mine for the most part. Claim blocks along this trend were controlled by Kennecott, Santa Fe Minerals, Minerals Engineering, Mariah Resources Ltd., Boise Creek Resources Ltd., Anglo Canadian Mines Corp., and others.

Romarco Minerals Inc. reportedly postponed its 1999 exploration drill program on its Sonoma Canyon Project in the northeastern portion of the Masonic District until year 2000 to allow additional time to evaluate and finalize the permitting process, which was completed in November 1999. The Sonoma Canyon Project consists of 57 claims, totaling about 1140 acres, located in the Walker Lane structural trend. Rock units within the project area have been intensely altered and commonly contain anomalous amounts of gold and copper mineralization. (This MRDS reported could not determine the location of the Romarco Minerals Project.)

Two principal areas of interest with regard to modern, bulk-mineable gold deposits in the Masonic District include: 1) a northeast trending belt which includes, from southwest to northeast, the Chemung, Lakeview, Red Rock, and Serita mines, in the western and central portions of the district west of the California-Nevada state line; and 2) the Sonoma Canyon Project reportedly in the northeast portion of the district east of the California-Nevada state line.

Companies that have actively explored the Chemung-Serita trend include, among others, Kennecott and Santa Fe Minerals (Strachan, 1987). Romarco Minerals Inc. reportedly initiated the Sonoma Canyon Project (Tingley and LaPointe, 2000). Whitney and Whitney, Inc. (2007) reportedly produced a technical report and pre-feasibility study for Anglo Canadian Mining Corp (http://www.whitneywhitney.com/projects.shtml). Anglo's area of interest in the Masonic District is not known to this MRDS reporter.

Sonoma Canyon is in the northeastern part of the Masonic District. The Sonoma Canyon Project reportedly consisted of a proposed drilling program that was to begin in 2000. The project covered 57 claims, totaling about 1140 acres, and was located in the Walker Lane structural trend. Rock units in the project area reportedly are intensely altered and commonly contain anomalous gold and copper mineralization. This MRDS reporter could not determine the precise location of the Sonoma Canyon Project, and did not find any definitive information on geology, mineralization, or resources associated with the Sonoma Canyon Project.

Post-1980 projects:

1a. Sarita (Serita) (aka Masonic) project (1981-84): 50 claims covering Sarita and other properties; Santa Fe Minerals, Optionee; Minerals Engineering Co., Optionor (33 unpatented and 3 patented claims); - Mines Co., NSR (14 unpatented claims). Includes historic underground, and surface mine workings and mine dumps. Claims form a contiguous block 2.6 miles (4.2 km) long and more than 0.5 mile (0.8 km) wide at the widest point.

Reconnaissance of the area revealed a number of mine workings and open cuts scattered along a mineralized and altered structure. Numerous mine dumps at Masonic were sampled by backhoe/trenching and several holes were drilled in the Lakeview and Sarita areas to further define the limits of the mineralization.

Metallurgical tests showed very good recoveries under laboratory-simulated heap-leaching conditions for typical low-grade ore.
Modern Exploration for Bulk-mineable Deposits (continued)

Plans called for heap-leaching of 55,000-110,000 metric tons (60,627-121,254 short tons) of open-pit ore and existing mine dumps with an anticipated gold grade of 0.11-0.17 troy ounces/metric ton (0.10-0.15 troy ounces/short ton). [Reserves estimate: approx. 15,000 troy ounces (0.5 metric tons) gold.]

1b. In 1985, Mariah Resources Ltd. acquired the option to purchase a 20 percent interest in a joint venture on the Masonic gold project. Mariah entered the joint venture with Boise Creek Resources Ltd. Boise Creek had executed formal agreements with both Anglo Canadian Mining Corp. and Mariah for the joint venture and development of the Masonic property.

Anglo granted an option to Boise and Mariah to acquire 50 percent (25 percent each) of Anglo Canadian's exclusive option by expending $200,000 on property payments and exploration and development work on the property by December 31, 1986.

The claim block covers approx. 3800 acres optioned from Minerals Engineering Co. (MECO) of Englewood, Colorado. Previous operators, including spent in excess of $1 million (Canadian) on the property for exploration and development.

The exploratory work centered around two mineral occurrences: the Sarita and Lakeview deposits. The most significant mineralization appeared to be in the Sarita pit, where over 10,000 feet of diamond drilling by Meco and Santa Fe Mining Inc. outlined ore reserves grading 0.09 to 0.14 ounces gold per ton and 0.30 to 6.0 ounces silver per ton.

At the Lakeview mine area, located west of the Sarita pit, the silver values are higher, with one drill returning a grade of 5.0 ounces silver per ton. Other holes drilled in the area intercepted gold mineralization with values between 0.04 and 0.12 ounces gold per ton. Five additional known mineral occurrences remained unexplored.

Historically, the property yielded sporadic production from 1907 until the early 1950s. Mining between 1951 and 1952 yielded 35 tons per day grading 0.17 ounces gold per ton. The mine was closed in 1954. Since the 1954 closure, Minerals Engineering Co. and Santa Fe Mining Inc. have both conducted exploratory work consisting of geophysical surveying, metallurgical work, and reverse circulation drilling.

Anglo Canadian retained Whitney and Whitney, Inc., a geological consulting firm based in Reno, Nevada, to further evaluate the property. Whitney and Whitney proposed a conventional cyanidation process for precious metals' recovery. Metallurgical testing reportedly indicated a 94 percent recovery of gold. Operating costs were estimated at $165 per ounce of gold recovered in the first two years of operation, at the rate of 400 tons per day. Costs were projected to be $184 per ounce during subsequent years. Mine live was projected to be nine years, and additional drilling was expected to increase proven reserves. [Reserves estimate: approx. 150,000 troy ounces (4.7 metric tons) gold.]

2. Sonoma Canyon Project (1999-2000): Romarco Minerals Inc. postponed the proposed 1999 exploration drill program on its Sonoma Canyon Project in the northeastern part of the Masonic District, Nevada, until year 2000 to allow additional time to evaluate the property and finalize the permitting process, which was completed in November 1999. The Sonoma Canyon Project consists of 57 claims, totaling about 1140 acres, located in the Walker Lane structural trend. The rock units within the project area have been intensely altered and commonly contain anomalous amounts of gold and copper mineralization. [No reserve estimate.]

Current Development Status: No known active exploration or development in progress as of July 2007.

Comments on the environmental information

The Masonic District is 12 miles (19 kilometers) north-northwest of the historic mining townsite of Bodie, which is managed by California State Parks and the U.S. Bureau of Land Management in cooperation with Mono County and various environmental interest groups. The Masonic District is in the Toiyabe National Forest and is open to mineral entry. Unlike Bodie, the Masonic District does not contain many well-preserved historic buildings and is outside the Bodie Bowl, which was designated an Area of Critical Environmental Concern in 1993 by the U.S. Bureau of Land Management. The Bodie Protection Act of 1994 prohibited the Bodie Bowl from being available for any mineral mining, leasing, or disposal activities, except under valid existing claims. Purchase of the Bodie Project (a then-active gold exploration project) by California State Parks in 1997 ended all future development of the mineral resources in the Bodie Project area.

The Masonic District occurs along a northeasterly structural trend at the northern end of the Bodie Hills. Prominent physiographic features include, from southwest to northeast, Masonic Mountain (9200? feet elevation), New York Hill (8620? feet elevation), Masonic Gulch (7600-8000? feet elevation), and Dome Hill (8100? feet elevation). Drainage from the district is generally rapid and to the west, north, and northeast into Walker Lake via the East Walker and Walker rivers. The semi-arid climate supports sagebrush, rabbitbrush, bitterbrush, cacti, pinyon pine, juniper, and various grass series. Mean annual precipitation is about 12 to 25 inches, much of which is snow. Mean annual temperature is about 32? to 48? F. The mean freeze-free period is in the range of 25 to 100 days.

Current Land Status:
The Masonic District consists of patented lands within the Toiyabe National Forest.

Reference information

Bibliographic references

Deposit

Berger, B. R., 1987, Descriptive model of epithermal quartz-alunite Au, in Mineral Deposit Models: U.S. Geological Survey Bulletin 1693, p. 158-159.
Deposit

Boalich, E. S., 1923, Mono County, Masonic District: California State Mining Bureau Report 18, p. 415-416.
Deposit

Chender, M., and Fordham, W., 1983, Sarita (Project): The Minesearch Annual, California, Oregon, and Washington, Metals Economic Group, v. VIII, p. 289-291.
Deposit

Chesterman, C. W., Chapman, R. H., and Gray, C. H., Jr., 1986, Geology and ore deposits of the Bodie mining district: California Division of Mines and Geology Bulletin 206, 35 pages, 5 plates, 11 figures, 7 tables, 17 photographs.
Deposit

Clark, W. B., 1970, Gold districts of California: California Division of Mines and Geology Bulletin 193, p. 150.
Deposit

Clark, W. B., 1998, Bodie District, in Gold Districts of California, Sesquicentennial Edition, California Gold Discovery to Statehood: California Division of Mines and Geology Bulletin 193, p. 147-148.
Deposit

Eakle, A. S., and McLaughlin, R. P., 1919, Mono County, Masonic District: California State Mining Bureau Report 15, p. 160-165.
Deposit

Heald, P., Foley, N. K., and Hayba, D. O., 1987, Comparative anatomy of volcanic-hosted epithermal deposits: acid-sulfate and adularia-sericite types: Economic Geology, v. 82, no. 1, p. 1-25.
Deposit

Johnson, R. F., 1951, Geology of the Masonic mining district, Mono County, California: M.A. thesis, Univ. of Calif. Berkeley, 51 p.
Deposit

King, T.V.V., Berger, B.R., Ridley, Ian, and Clark, R.N., 1996, in Green, R.O., Editor, Defining the interdependence of volcanism, tectonism, and fluid availability in the formation of epithermal mineralization at Aurora-Bodie CA/NV using AVIRIS Data: Summaries of the Sixth Annual JPL Airborne Earth Science Workshop, March 4-8, 1996, Vol. 1, AVIRIS Workshop, JPL Publication 96-4, Vol. 1, p. 149-154 (also: ftp://popo.jpl.nasa.gov/pub/docs/workshops/96_docs/21.PDF)
Deposit

Legend Metallurgical Laboratory, Reno, NV, 1988, Letter report in California Geological Survey Minefile Folder No. 322-6121.
Deposit

Mono County Historical Society 2004 Newsletter, Masonic Mining District: http://www.cagenweb.com/com/mono/historicalsociety/2004newsletter.txt, 4 p.
Deposit

North American Gold Mining Industry News, 1985, Mariah picks up option on Masonic gold property: North Am. Gold Mining Industry News, November 22, 1985, v. 3, issue 27, 2 p.
Deposit

Sampson, R. J., and Tucker, W. B., 1940, Mineral resources of Mono County: California Journal of Mines and Geology, Report of State Mineralogist, v. 36, no. 2, p. 115-156.
Deposit

Strachan, June 1987, Chemung Hill: unpublished consulting report, a portion of which (pp. 287-291) is in the California Geological Survey Minefile Folder No. 322-6121.
Deposit

Tingley, J. V., and LaPointe, D. D., 2000, Masonic District, in The Nevada Mineral Industry 1999: Nevada Bureau of Mines and Geology Special Publication MI-1999, p. 22.
Deposit

Whitney and Whitney web site: http://www.whitneywhitney.com/projects.shtml.
Deposit

Yahoo Mining/Metals News, 12/15/1999; Elko Daily Free Press, 12/24/1999, referenced in: Masonic District in The Nevada mineral industry 1999, Nevada Bureau of Mines and Geology Special Publication MI-1999, p. 22.

General comments

Subject category	Comment text
Deposit	The Masonic District is characterized by Tertiary calc-alkaline volcanism occurring in a back-arc spreading environment. Pre-Cretaceous crystalline basement includes quartz-feldspar-mica schists and hornfels (amphibolite grade locally) intruded by pre-Tertiary biotite granodiorite (locally quartz monzonite) and lesser granite. Regional stratigraphic studies suggest the Fletcher Basin area, including what is now the Masonic district, received from 1000 to over 3000 feet of andesite flows, tuffs, and lahars in the early Miocene. Later Miocene and early Pliocene tuffaceous sediments added an additional 1000 to 3000 feet. The andesite tuff-andesite porphyry-andesite lahar sequence exposed on Chemung Hill is typical of the early Miocene, and the sequence is offset across the northeasterly-trending Chemung Hill structure. Northwest tilting at Masonic was most likely concurrent with the latter stages of tuffaceous deposition, and prior to mineralization. At Chemung Hill, movement along the northeast structure post-dated tilting and possibly erosion of much of the tuffaceous section, and subsequent epithermal fluids, associated with precious metals mineralization, vented onto an erosional unconformity. The fluids appear to have vented onto basal tuffaceous sediments or, if pre-mineral erosion was severe enough, perhaps onto a paleosurface with exposed, northwest-dipping Miocene andesites. In either case, that paleosurface has been eroded from the Chemung Hill area, exposing what is interpreted as the structurally-controlled "feeders" to vents of a fossil epithermal system. Opaline textures and lack of banding in the quartz veins is interpreted to indicate that the paleosurface was less than 1000 feet above the present surface of Chemung Hill. The presence of crystalline alunite in silica, and narrow kaolin selvages, combined with an observed lack of sericite in wall rocks, indicate Chemung Hill (and three other areas described in Strachan's report) is an acid sulfate epithermal system (Heald and others, 1987, p. 8; cited in Strachan, 1987, p. 5). Stratigraphy, its relation to mineralized structures, and the observed style of alteration suggest no epithermal vent-related, or paleosurface-related, disseminated gold mineralization is preserved at Chemung Hill.

Subject category

Comment text

Deposit

The Masonic District is characterized by Tertiary calc-alkaline volcanism occurring in a back-arc spreading environment. Pre-Cretaceous crystalline basement includes quartz-feldspar-mica schists and hornfels (amphibolite grade locally) intruded by pre-Tertiary biotite granodiorite (locally quartz monzonite) and lesser granite.

Regional stratigraphic studies suggest the Fletcher Basin area, including what is now the Masonic district, received from 1000 to over 3000 feet of andesite flows, tuffs, and lahars in the early Miocene. Later Miocene and early Pliocene tuffaceous sediments added an additional 1000 to 3000 feet. The andesite tuff-andesite porphyry-andesite lahar sequence exposed on Chemung Hill is typical of the early Miocene, and the sequence is offset across the northeasterly-trending Chemung Hill structure.

Northwest tilting at Masonic was most likely concurrent with the latter stages of tuffaceous deposition, and prior to mineralization. At Chemung Hill, movement along the northeast structure post-dated tilting and possibly erosion of much of the tuffaceous section, and subsequent epithermal fluids, associated with precious metals mineralization, vented onto an erosional unconformity. The fluids appear to have vented onto basal tuffaceous sediments or, if pre-mineral erosion was severe enough, perhaps onto a paleosurface with exposed, northwest-dipping Miocene andesites. In either case, that paleosurface has been eroded from the Chemung Hill area, exposing what is interpreted as the structurally-controlled "feeders" to vents of a fossil epithermal system. Opaline textures and lack of banding in the quartz veins is interpreted to indicate that the paleosurface was less than 1000 feet above the present surface of Chemung Hill.

The presence of crystalline alunite in silica, and narrow kaolin selvages, combined with an observed lack of sericite in wall rocks, indicate Chemung Hill (and three other areas described in Strachan's report) is an acid sulfate epithermal system (Heald and others, 1987, p. 8; cited in Strachan, 1987, p. 5).

Stratigraphy, its relation to mineralized structures, and the observed style of alteration suggest no epithermal vent-related, or paleosurface-related, disseminated gold mineralization is preserved at Chemung Hill.

Reporter information

Type	Date	Name	Affiliation	Comment
Reporter	31-AUG-2007	Hill, Robert, L.	California Geological Survey CGS (Formerly CDMG)
Editor	20-FEB-2008	Schruben, Paul G.	U.S. Geological Survey	Converted from S&A FileMaker format to Oracle. Edit checks on rocks, units, and ages with Geolex search, and other fields.

Beyond USGS

Supplemental information added by qvyshift.com. Not part of the original USGS MRDS record.

Maps centered on this site

Authoritative California resources

These are landing pages for further research — the state agencies don't currently expose per-mine deep links.