Cordero Mine

Site Name

Primary: Cordero Mine
Secondary: Mcdermitt Group

---

Commodity

Primary: Mercury

---

Location

State: Nevada
County: Humboldt
District: Opalite Mining District

---

Land Status

Land ownership: BLM Administrative Area
Note: the land ownership field only identifies whether the area the mine is in is generally on public lands like Forest Service or BLM land, or if it is in an area that is generally private property. It does not definitively identify property status, nor does it indicate claim status or whether an area is open to prospecting. Always respect private property.

---

Holdings

Not available

---

Workings

Type: Surface/Underground

---

Ownership

Owner Name: Cordero Mining Co.
Years: 1970 -

---

Production

Year: 1970
Time Period: 1941-1970
Material type: HG
Description: Cp_Grade: ^10-15 Lb/Ton

---

Deposit

Record Type: Site
Operation Category: Past Producer
Operation Type: Surface-Underground
Year First Production: 1935
Discovery Year: 1924
Discovery Method: Ore-Mineral In Place
Years of Production:
Organization:
Significant: Y
Deposit Size: L

---

Physiography

General Physiographic Area: Intermontane Plateaus
Physiographic Province: Basin And Range Province
Physiographic Section: Great Basin
Physiographic Detail: Basin And Mountains

---

Mineral Deposit Model

Model Name: Hot-spring Hg

---

Orebody

Form: BLANKET

---

Structure

Type: R
Description: Reg.Struct: Mcdermitt Caldera Collapse Structure: Arcuate Faults And Ring Fractures ; Reg.Trends: Northeast

Type: L
Description: Ne-Trending Faults; "M" Fault

---

Alterations

Alteration Type: L
Alteration Text: Silicic, Argillic

---

Rocks

Name: Andesite
Role: Associated
Age Type: Associated Rock
Age Young: Pliocene

Name: Andesite
Role: Associated
Age Type: Associated Rock Unit
Age Young: Miocene

---

Analytical Data

Analytical Data: EARLY ORE RAN 15 LB. HG/TON ORE. ASSAYS IN 1937 RAN FROM 0.05 TO 1.78% HG.

---

Materials

Ore: Hematite
Ore: Stibnite
Ore: Pyrite
Ore: Cinnabar
Ore: Mercury
Gangue: Alunite
Gangue: Jarosite
Gangue: Opal
Gangue: Chalcedony
Gangue: Quartz

---

Comments

Comment (Deposit): DISCOVERED IN 1924 BY TOMAS ALCORTA. THE NAME "CORDERO" IS DERIVED FROM THE BASQUE LANGUAGE MEANING "LITTLE LAMB," AFTER THE ORIGINAL DISCOVERY OF ORE BY BASQUE SHEEPHERDERS DURING THE LAMBING SEASON. ALCORTA AND HIS PARTNER E. AGNAREZ EXPLORED FOR SEVERAL YEARS BY PITS. IN 1935, THE BRADLEY MINING CO. LEASED IT AND SANK SHAFT INTO THE MAIN ORE BODY. SINCE 1940, CORDERO MINING CO. HAS EXPLORED AND MID THE PROPERTY. IT RAPIDLY BECAME NEVADA'S LEADING PRODUCER OF MERCURY. MINE WORKINGS IN 1944 CONSISTED OF 6 OPEN PITS AND ABOUT 3000 FT. OF UNDERGROUND WORKINGS. IT CLOSED IN 1970. RECENT EXPLORATION (1976) DELINEATED A NEW ORE BODY AT CORDERO, WITH RESERVES OF ABOUT 400,000 FLASKS HG. ; INFO.SRC : 1 PUB LIT

Comment (Commodity): REPORTED "METACINNABAR" IS ACTUALLY PHOTOTROPHICALLY ALTERED CORDEROITE (WHICH IS STILL CHEMICALLY CORDEROITE). JOHN MCCORMACK, ORAL COMMUNICATION 30 AUG/91.

Comment (Reserve-Resource): ITEMS 1 - 3 TOTAL APPROX. 60,000 FL. (1949) ITEM 4 EST. AS OF 1961.

Comment (General): HERRESHOFF;4 FT, 12 HEARTH (1941) [moved from references of deleted record 10125266]

Comment (Deposit): Ore to 600 ft (Bailey and Phoenix, 1944, p. 98).

Comment (Production): 1941-1970, OVER 115,000 FLASKS HG FROM 1.8% HG ORE (from Willden, 1964)

Comment (Development): MINE CLOSED UNDERGROUND WORKINGS IN 1970, BUT OPENED THE MCDERMITT OPEN PIT MINE NEARBY.

Comment (Deposit): REPLACEMENT AND FRACTURE FILLING OCCURS BENEATH FAULTS AND IN OPALITE

Comment (Workings): PITS, SHAFTS, DRIFTS

Comment (Geology): CINNABAR OCCURS AS DISSEMINATED CRYSTALS AS VEINLETS, AND AS SOLID MASSES IN ALTERED VOLCANICS. TUFFACEOUS SEDIMENTARY ROCKS CONSIDERED TO BE CALDERA-FILL. ; GEOL.DESC: RHYOLITE OVERLIES ANDESITE ; MAJOR.UNITS: MIOCENE VOLCANIC ROCKS

Comment (Geology): TWO OR MORE SILICIFIED ZONES (Yates, 1942, p. 348).

---

References

Reference (Deposit): J.E. GILBERT AND V.P. HAAS, 1959, CORDERO-NEVADA'S LARGEST MG. MINE; E. MIN. JOUR., VOL. 160, NO. 3.

Reference (Deposit): ROPER, M.W., 1976, HOT SPRINGS MERCURY DEPOSITION AT MCDERMITT MINE, HUMBOLDT CO., NEV; PREPRINT OF PAPER GIVEN AT AIME ANNUAL MEETING LAS VEGAS, NEV. 1976.

Reference (Deposit): YATES, R.G., 1942, QUICK SILVER DEPOSITS OF THE OPALITE DISTRICT, MALHEUR COUNTY, OREGON, AND HUMBOLDT COUNTY, NEVADA; U.S.G.S. BULL. 931-N, p. 346, 348.

Reference (Deposit): FOORD, E.E. BRENDSEN, P., STOREY, L., 1974, CORDEROITE, FIRST NATURAL OCCURRENCE OF DHG3S2CU2 FROM THE CORDERO MERCURY DEPOSIT, HUMBOLDT CO., NEV; AM.MIN., VOL 59, P. 652-655.

Reference (Deposit): MCKEE, E.H., 1976, ORIGIN OF THE MCDERMITT CALDERA IN NEVADA AND OREGON AND RELATED MERCURY DEPOSITS: PREPRINT OF A PAPER PRESENTED AT THE 1976 AIME ANNUAL MEETING, LAS VEGAS, NEVADA, 1976.

Reference (Deposit): BAILEY, E.H., AND PHOENIX, D.A., 1944, QUICK SILVER DEPOSITS IN NEVADA; UNIV. NEV. BULL. 38, NO. 5; GEOL AND MIN. SER NO. 41, p. 98, pl. 1.

Reference (Deposit): RYTUBA, J.J., 1976, GEOLOGY AND ORE DEPOSITS OF THMCDERMITT CALDERA, NEVADA-OREGON; U.S.G.S. OPEN FILE REPT. 76-535

Reference (Deposit): USBM IC 6995,1938,P.31

Reference (Deposit): USGS BULL 931-N,P.346

Reference (Deposit): WILLDEN, R., 1964, GEOLOGY AND MINERAL DEPOSITS OF HUMBOLDT CO. NEV.; NEV. BUREAU OF MINES BULL. 59.

Reference (Deposit): U.S. GEO SUR BULL 931-N, P.346

Reference (Deposit): USBM IC 8252,1965,P.224

---

Nevada Gold

Nevada has a total of 368 distinct gold districts. Of the of those, just 36 are major producers with production and/or reserves of over 1,000,000 ounces, 49 have production and/or reserves of over 100,000 ounces, with the rest having less than 100,000 ounces. Read more: Gold Districts of Nevada.