Exposed Reef Mines

The Exposed Reef Mines is a copper and silver mine located in Santa Cruz county, Arizona at an elevation of 4,350 feet.

About the MRDS Data:

All mine locations were obtained from the USGS Mineral Resources Data System. The locations and other information in this database have not been verified for accuracy. It should be assumed that all mines are on private property.

Mine Info

Satelite View

MRDS mine locations are often very general, and in some cases are incorrect. Some mine remains have been covered or removed by modern industrial activity or by development of things like housing. The satellite view offers a quick glimpse as to whether the MRDS location corresponds to visible mine remains.

Site Name

Primary: Exposed Reef Mines
Secondary: Blue Eagle and Exposed Reef Group
Secondary: Saint Louis Mine

Commodity

Primary: Copper
Primary: Silver
Secondary: Lead
Secondary: Zinc
Secondary: Gold
Tertiary: Iron

Location

State: Arizona
County: Santa Cruz
District: Harshaw District

Land Status

Land ownership: National Forest
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: Underground

Ownership

Owner Name: De Saulles, Albert
Years: 1953 -

Owner Name: Sibold, Helen And Doris
Years: 1953 -

Production

Not available

Deposit

Record Type: Site
Operation Category: Producer
Operation Type: Unknown
Discovery Year: 1875
Years of Production:
Organization:
Significant: N
Deposit Size: S

Physiography

General Physiographic Area: Intermontane Plateaus
Physiographic Province: Basin And Range Province
Physiographic Section: Sonoran Desert

Mineral Deposit Model

Not available

Orebody

Form: IRREGULAR

Form: IRREGULAR

Structure

Type: R
Description: General Structure Common To Regional Formations Is A Sheeting Which Dips 40 Nnw

Type: L
Description: Main Vein Paralleled By Banded Iron Formation-Hematite Dike Showing Some Copper Stain, And By Several Smaller Parallel Quartz Veins; 5 Principal Veins On Property

Alterations

Alteration Type: L
Alteration Text: Extensive Surface Oxidation

Rocks

Name: Diorite
Role: Associated
Age Type: Host Rock
Age Young: Late Cretaceous

Name: Diorite
Role: Associated
Age Type: Associated Rock
Age Young: Late Cretaceous

Analytical Data

Analytical Data: ASSAY VALUES AVERAGED 15% CU, 15 OZ./TON AG, $2.00/TON AU

Materials

Ore: Bornite
Ore: Sphalerite
Ore: Chalcocite
Ore: Galena
Ore: Chalcopyrite
Ore: Tetrahedrite
Ore: Cuprite
Ore: Pyrite
Gangue: Hematite

Comments

Comment (Commodity): ORES OF EXPOSED REEF AND BLUE EAGLE GROUPS ARE PRIMARILY ARGENTIFEROUS COPPERS WITH SOME GOLD A ND STRONG IRON CONTENT

Comment (Production): NO RECORDS OF PRODUCTION

Comment (Deposit): Discovery Year: LATE 1800'S

Comment (Deposit): SEE ALSO: BLUE EAGLE MINE, INVINCIBLE PROSPECT ; INFO.SRC : 1 PUB LIT; 2 UNPUB REPT

Comment (Geology): CLAIMS LOCATED ON LARGE BELT OF COARSE RHYOLITE PORPHYRY THAT INCLUDES NEARLY ALL OF RED MOUNTAIN; PORPHYRY BELT IS PROFUSELY IMPREGNATED WITH CRYSTALS AND GRAINS OF PYRITE, CHALCOPYRITE, AND CHALCOCITE

Comment (Development): EXPOSED REEF AND BLUE EAGLE PROPERTIES COMPRISE 22 LODE CLAIMS TOTALLING 440 ACRES AND INCLUDING CLAIMS OF BORDER PATROL, LIME BANK NO.1-5, DONNA MARIA, MILL SITE, REED TUNNEL, IRON BANK, BLUE EAGLE NO. 1-2, ST. LOUIS, NORTH STAR, LOG CABIN, COW BOY POWDER HOUSE, EXPOSED REEF, SILVER TUNN EL LUCKY DAY, SILVER STAR INVINCIBLE, ST. PATRICKS, OLD BOY ROGERS, RE D FOX NO. 1-4; OWNERS INCLUDED JOHN FARLEY D. DOWD, J.B. SHANNON

Comment (Deposit): NUMEROUS VEINS ON PROPERTY CONTAINING LOW-GRADE SULFIDE ORES; MAIN VEIN TRENDS NW-SE ACROSS SEVERAL CLAIMS; VEINS GENERALLY HAVE VERY WIDE MINERALIZED OUTCROP COPPER ORE BODIES THAT INCREASE, BOTH IN SIZE AND VALUES, WITH DEPTH; VEINS VARY IN WIDTH FROM 1-30 FT

Comment (Workings): DEVELOPMENTS INCLUDED 312-FT DEEP EXPOSED REEF SHAFT; 36-FT LONG TUNNEL AND OPEN-CUT ON SAINT LOUIS CLAIM.500 FT EXPOSED REEF TUNNEL THAT CUTS 3 VEINS; NUMBEROUS WINZES AND RAISES EXTENDING FROM SHAFTS AND TUNNELS; 300-FT TUNNEL AND 112-FTSHAFT ON RED FOX NO.1 CLAIM; TOTAL OF 11 TUNNELS, FROM 10-500 FT LONG, ON PROPERTY; 600 FT OF DRIFTS AND CROSSCUTS

Comment (Location): LOCATED ON NE SIDE OF ALUM GULCH; BLUE EAGLE GROUP LOCATED 1/2 MILE TO SW, ON SOUTH SIDE OF ALUM GULCH ; INFO FROM LAND.ST :(1979)

References

Reference (Deposit): SIMONS, FRANK S., 1972, MESOZOIC STRATIGRAPHY OF THE PATAGONIA MOUNTAINS AND ADJOINING AREAS, SANTA CRUZ COUNTY, ARIZONA; USGS PROFESSSIONAL PAPER 658-E

Reference (Deposit): ABGMT CLIPPINGS FILE, EXPOSED REEF MINE

Reference (Deposit): MOORES, RICHARD C., 1972, THE GEOLOGY AND ORE DEPOSITS OF A PORTION OF THE HARSHAW DISTRICT, SANTA CRUZ COUNTY, ARIZONA; M.S. THESIS, UNIVERSITY OF ARIZONA

Reference (Deposit): USBM FILES, EXPOSED REEF MINES

Reference (Deposit): ADMR FILE DATA, EXPOSED REEF AND BLUE EAGLE GROUPS

Reference (Deposit): ABGMT FILES, STANTON B. KEITH

Reference (Deposit): SCHRADER, FRANK C., 1915, MINERAL DEPOSITS OF THE SANTA RITA AND PATAGONIA MOUNTAINS, ARIZONA; USGS BULLETIN 582, P.257-258

Reference (Deposit): SIMONS, FRANK S., 1974, GEOLOGIC MAP AND SECTIONS OF THE NOGALES AND LOCHIEL QUADRANGLES, SANTA CRUZ COUNTY, ARIZONA; USGS MAP I-762 (1:48000)

Arizona Gold

"Where to Find Gold in Arizona" looks at the density of modern placer mining claims along with historical gold mining locations and mining district descriptions to determine areas of high gold discovery potential in Arizona. Read more: Where to Find Gold in Arizona.