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Jessup Gold Prospect

Past Producer in Churchill county in Nevada, United States with commodities Gold, Silver, Mercury, Arsenic, Antimony, Tungsten
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Sections on this page
  1. Identification information
  2. Geographic coordinates
  3. Site location context
  4. Geographic areas
  5. Public Land Survey System information
  6. Commodities
  7. Materials information
  8. Alteration
  9. Mineral occurrence model information
  10. Host and associated rocks
  11. Nearby scientific data
  12. Geologic structures
  13. Ore body information
  14. Controls for ore emplacement
  15. Economic information about the deposit and operations
  16. Mining district
  17. Land status
  18. Ownership information
  19. Links to other databases
  20. Bibliographic references
  21. General comments
  22. Reporter information

Geologic information

Identification information

Deposit ID 10310348
Record type Site
Current site name Jessup Gold Prospect
Alternate or previous names Central Jessup District, Gold King claim (Central Jessup district), Valley King claims (Central Jessup district), San Jacinto Zone, San Jacinto South Zone, San Jacinto West Zone, North Jessup Property

Geographic coordinates

Point of reference Geographic coordinates: Elevation UTM Precision Relative position Point location
-118.8796, 39.94683 (WGS84) 2000 The Jessup Gold Prospect is located in the central Jessup district just north of Interstate 80, about 40 kilometers southwest of Lovelock and 100 km NE of Reno., 1750
(click for info)
Ore Body -118.85988, 39.95795 (WGS84) 100 These coordinates are for the North Jessup orebody.

Site location context

Political divisions (FIPS codes)

Churchill(county)

Nevada(state)

United States(country)

North America(continent)

Land(continent)

USGS map quadrangles

Jessup(quadrangle 1:24,000 scale)

Carson Sink(quadrangle 1:100,000 scale)

Reno(quadrangle 1:250,000 scale)

Hydrologic units (watersheds)

Lower Humboldt(hydrologic unit)

Humboldt(hydrologic accounting unit)

Black Rock Desert-Humboldt(hydrologic subregion)

Great Basin(hydrologic region)

Federal lands

Bureau of Land Management(Bureau of Land Management NV)

Bureau of Land Management NV BLM(Type of land area)

BLM(Federal land areas administered by BLM)

Geographic areas

Country State County
United States Nevada Churchill

Public Land Survey System information

Meridian Township Range Section Fraction State
Mount Diablo 024N 028E 07 08 16 17 18 20 Nevada
Mount Diablo 024N 027E 11 12 13 14 24 Nevada

Comments on the location information

  • UTM is to geographic center of the three main Jessup deposit target areas. North Jessup is 1.3 mi to the ENE, but the edges of the orebodies are probably within 1km. So North Jessup was merged into Jessup.

Commodities

Commodity Importance
Gold Primary
Silver Primary
Mercury Tertiary
Arsenic Critical Tertiary
Antimony Critical Tertiary
Tungsten Critical Tertiary

Comments on the commodity information

  • Ore Materials: free gold, cerargyrite, scheelite
  • Gangue Materials: quartz, iron oxides

Materials information

Materials Type of material
Gold Ore
Cerargyrite Ore
Scheelite Ore
Quartz Gangue

Alteration

  • (Local) There is widespread argillic and limonitic alteration with associated silicification and mineralization. Altered volcanic rocks show characteristically anomalous geochemical signatures in mercury, arsenic, and antimony. Alteration is that typically associated with volcanic-hosted epithermal systems and consists of blanket argillic bleaching with disseminated limonite (pyrite at depth) along a broad arc across the district. All gold mineralization in the district appears to be associated with this regional alteration pattern, which in turn is controlled by both caldera structures and rock permeability. The lapilli tuffs appear to be the most permeable rocks in the area.Alteration and mineralization post-date the rhyolite.

Mineral occurrence model information

Model code 150
USGS model code 25c
Deposit model name Epithermal vein, Comstock
Mark3 model number 16

Host and associated rocks

  • Host or associated Host
    Rock type Metamorphic Rock > Metavolcanic Rock
    Stratigraphic age (youngest) Mesozoic
  • Host or associated Host
    Rock type Volcanic Rock (Aphanitic) > Intermediate Volcanic Rock > Andesite
    Stratigraphic age (youngest) Paleocene
  • Host or associated Host
    Rock type Volcanic Rock (Aphanitic) > Felsic Volcanic Rock > Rhyolite
    Stratigraphic age (youngest) Paleocene

Nearby scientific data

(1) -118.8796, 39.94683
ListMap
Ore Body (2) -118.85988, 39.95795
ListMap

Economic information

Geologic structures

Type of structure Local
Structure description NE-trending faults. Structural deformation in the Jessup area was episodic and controlled mainly by caldera-related structures, which are predominantly normal faults along ring fractures. These structures appear to have been reactivated following lithification of the basin-fill material.

Ore body information

  • General form tabular to blanket to irregular

Controls for ore emplacement

  • Locally, ore occurs in a crushed zone associated with NE-trending faults. In general there are both lithologic and structural controls to mineralization, associated with the more permeable units of the caldera complex and with the caldera ring fracture system. At the North Jessup property ore is controlled by rhyolite plugs.

Comments on the geologic information

  • Earlier work indicates that the Jessup area hosts a Tertiary volcanic caldera complex with associated epithermal gold mineralization controlled by faulting along the caldera margins.

    The oldest recognized rocks within the prospected area are Triassic-Jurassic basalts which are metamorphosed to upper greenschist/ lower amphibolite facies. A series of caldera-related Tertiary volcanic and sedimentary rocks unconformably overlies the Mesozoic basement rocks. These volcanics range in composition from andesite to rhyolite. This period of Tertiary volcanism initiated with the eruption of a few hundred meter thickness of subaerial andesites. This phase terminated with the collapse of the central area forming a large caldera, controlled by a series of ring fractures. Erosion of these andesites in the northern part of the caldera produced thin layers of andesitic sand and conglomerate preserved in isolated portions of the caldera. As subsidence continued in the central part of the caldera, fine-grained clastic sediments and chert were deposited in lakes, followed by ignimbrite deposits of rhyolitic lapilli tuff. Andesitic volcanism followed, and renewed collapse of the caldera along the ring fractures accompanied by emplacement of rhyolitic flows, domes, and dikes.

Economic information about the deposit and operations

Operation type Surface-Underground
Development status Past Producer
Deposit size Small
Significant Yes
Discovery year 1908
Discoverer Frank Jessup & L.H. Murray
Year of first production 1908
Year of last production 1940
Production years 1908-1940, sporadically

Mining district

District name Jessup District

Land status

Ownership category Private
Ownership category BLM Administrative Area
Area name Winnemucca BLM District

Ownership information

  • Type Owner
    Owner Alex Von Hafften
    Year 1999
  • Type Owner-Operator
    Owner Echo Bay
  • Type Operator
    Owner Southwestern Gold Corporation
    Year 1992

Comments on the workings information

  • Development consists of an older 200-ft. shaft with 1000 ft. of workings, pits, and more recent surface prospecting and repeated episodes of drilling. The North Jessup property is developed by an old vertical shaft and underground workings that probably exceed 200 feet in total extent. More recent surface prospecting has been conducted in the area.

Comments on other economic factors

  • Santa Fe Pacific Minerals reportedly delineated a geological resource of a million tonnes of ore grading 0.31 opt gold (sic) on the San Jacinto South zone in 1985. ( typo?should be .031 opt?)

    After drilling, Southwestern Gold Corporation geologists calculated a mineral inventory for the combined San Jacinto Mine area, San Jacinto South, and the Central Jessup area of 1,492,000. tons of ore with average grade of 0.035 opt gold and 0.37 opt silver to a maximum depth of 250 feet, minable by open pit methods.

    Pan-Nevada Gold Corp. in 2006 was re-evaluating the resource, but it was reportedly at:

    resource = 8,370,000 tons grading 0.025 opt Au, 0.25 opt Ag inferred.

Comments on development

  • Jessup Gold Prospect

    The Gold King was the original discovery claim, adjoining the Valley King Group which claims produced about 1000 ounces of gold in 1908-1909. In 1932, Olaf Johnson discovered placer gold on top of a small hill on the Valley King claim and several ounces of gold were produced there by dry-washing. The claims were under lease to Kenneth Dale and Dick Collins in 1938.

    The property has attracted exploration for epithermal gold mineralization since the 1960s and 1970s, when Great Basin Exploration drilled one shallow rotary drillhole on the prospect and Simplot excavated a number of trenches. In 1982, Occidental Petroleum conducted surface sampling and geologic mapping and drilled 13 rotary holes totaling 4165 feet in the San Jacinto and Central Jessup areas. Also in 1982, Cordex Syndicate mapped and sampled the entire district and drilled 42 vertical and angle holes totaling 15,655 feet in the San Jacinto West, San Jacinto South, San Jacinto, Central Jessup, North Jessup, Miing Lady and Tosh Hill areas. Cordex dropped the property in 1983 following this work. Santa Fe Pacific Minerals mapped and sampled the district in 1985, and drilled 23 rotary holes totaling 8700 feet, which reportedly delineated a geological resource of a million tonnes grading 0.31 opt gold on the San Jacinto South zone.

    In 1986, Bullion Mountain Mining Company reported a gold discovery in the Jessup District and delineated a gold-mineralized zone 100 feet wide and 7000 feet long containing values as high as 0.27 opt gold from surface sampling. The prospect was described as being adjacent to Long Lac Mineral Exploration Company's property in the same district. It is reported that Bullion's prospect was at the site of the old Gold Ore Claims.

    In 1988-1989, Draco Gold Mines of Tucson, AZ leased the property, was taken over by Amax Exploration who trenched the property in 1989 and drilled 10 RC angle holes in the San Jacinto West and Central Jessup areas. Amax relinquished the property in 1990.

    Southwestern Gold Corporation identified the Jessup district as an area of interest during a regional reconnaissance program in 1990-1991 involving detailed mapping, trenching, rock chip sampling, and geophysical surveys. In 1992 Southwest identified 5 targets within the district: San Jacinto Mine area, San Jacinto West, San Jacinto South, Central Jessup, and North Jessup. IP and magnetic surveys, trenching and sampling was done in these areas and defined a mineralized zone 100 feet by 700 feet grading up to .17 opt gold at the surface. A preliminary drilling program or 16 RC holes totaling 3720 feet was carried out in spring 1992 by SWG to test four of the target zones: San Jacinto Mine area, San Jacinto West, San Jacinto South, and Central Jessup. Metallurgical tests on two 50-kg samples indicated that the Jessup mineralized rock was very amenable to heap leach extraction of gold. Of the target areas, three contained gold mineralization of economic significance: the San Jacinto Mine area, San Jacinto South, and the Central Jessup area.

    SW signed a 10-year lease-option agreement on 91 claims with claim owner Alex Von Hafften and staked and additional 36 claims on the prospect. The property is in the "checkerboard" area of alternate section ownership by Santa Fe Corporation from original railroad land grants.

    Echo Bay discovered two deposits in this area for which the exact location is uncertain.

    In 2002, NDT Ventures Ltd. announced plans to explore the Hannah property in the Jessup district. Previous workers on the property obtained numerous gold values exceeding 0.03 opt Au over a large area of bleached and tourmalinized sedimentary rocks that could be traced over a strike length of almost 2,000 feet. The best gold assays (up to 0.5 opt Au) have been reported in iron-oxide-stained, silicified rocks. No drilling has been conducte
  • Jessup Gold Prospect (continued)

    In 2006, the Jessup property was owned by Pan-Nevada Gold Corp. who drilled 7 holes and reported high-grade gold values.



    North Jessup Property

    In October 1997, Americomm Resources Corp., announced that Echo Bay Exploration Inc. had successfully completed a third round of exploration drilling on their Jessup Gold Property that identified a new gold resource area. Drilling to date on the 2,200-acre site totals 38,575-feet in 120 reverse circulation holes. Echo Bay, reported reserves present, but unknown in amount.

Reference information

Bibliographic references

General comments

Subject category Comment text
Deposit There are two types of gold occurrence in the Jessup District: subvertical quartz-breccia veins, and disseminated quartz stockworks. At the San Jacinto Mine, gold production was from an east- west-trending sub-vertical zone of hydrothermal alteration consisting of silicification and argillization associated with the San Jacinto fault zone in sedimentary/ignimbrite package. In the prospected areas, small veins up to one foot wide carry quartz and iron oxides.

In 2006, Pan-Nevada?s high-grade drill intercept (55.7 grams per ton, or 1.625 ounces per ton) occurs within a stockwork of oxidized quartz-pyrite veinlets that are hosted by strong clay-altered andesite. The five foot interval includes veins up to ? inch wide. Another high grade mineralized zone appears clearly related to strongly-silicified ash tuff with frequent zones of hydrothermal breccia, similar to (and perhaps connected to) the San Jacinto Breccia Pipe. Breccia clasts are often obviously rotated and occur within a fine-grained matrix comprised of silica and pyrite, with pyrite locally up to 25 percent of the matrix. The 15 feet averaging 0.076 ounces per ton (445 feet to 460 feet) is related to a silicified zone in ash/pumice/lithic tuff breccia containing quartz-pyrite stringers. The 10 foot interval averaging 0.067 ounces per ton (490 feet to 500 feet) involves argillized ash/pumice/lithic tuff from 490 feet to 496 feet and then the upper part of a wide shear zone that extends from 496 feet to 520 feet.



The North Jessup property is developed in a rhyolite plug that intrudes metavolcanic rocks. The rhyolite is altered, with the feldspars and much of the groundmass converted to clay minerals and sericite. Irregular fractures extend through the rock with common iron staining and some silicification of the rhyolite adjacent to the fractures and with quartz seams in some of the fractures.

Surface work by Southwestern Gold Corporation in the North Jessup area identified a quartz stockwork about 25 feet square assaying up to 5.3 ppm gold. A 15-foot drill intersection had reported assays of 3.9 ppm Au. Surface mapping in the area combined with drill data suggests that the central portion of the North Jessup area consists of down-dropped blocks of strongly altered sediment and ignimbrite with both low-grade blanket-type and higher grade feeder-type mineralization present.

Reporter information

Type Date Name Affiliation Comment
Reporter 01-DEC-06 La Pointe, D. D. Nevada Bureau of Mines and Geology
Editor 01-SEP-07 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. Blended in and deleted DD's North Jessup record 10310349.

Beyond USGS

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

Maps centered on this site

Authoritative Nevada resources

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