Gold and Silver Deposits in Arizona, by County

Pearce Rhyolite with visible gold

Gold and Silver in Cochise County. Cochise County is in the southeastern corner of the state, gold is associated with copper, silver and lead in porphyry copper deposits in the Warren (Bisbee) district, associated with lead and silver ore in the Tombstone district, and the precious metal is found in vein and disseminated deposits in the Turquoise (Pearce) district. The gold and silver lodes at Pearce may be quite extensive with mineralization found described in several different deposits. Gold is reported in the Manzoro district of the Dragoon Mountains; and the Dos Cabezas and Teviston districts in the Dos Cabezas Mountains. Other deposits occur in the  Huachuca Mountains and in the Swisshelm Mountains. Gold placers occur in the Dos Cabezas, Teviston, Huachuca, Gleeson, Pearce, and Gold Gulch near Bisbee. For the most part, these are relatively small placers.  

Silver deposits in Cochise County are in the Tombstone district, where found as disseminated flakes at the Empire mine and as small masses of wire silver at the Flora Morrison mine. In the Warren (Bisbee) district, silver is found in small amounts in secondary chalcocite, and less commonly with halloysite. At the Commonwealth mine in the Turquoise (Pearce) district, silver is found with cerargyrite, embolite, and jarosite in hydrothermal veins.

Globe-Miami district

Gila County in east-central Arizona is a source for a small amount of gold from Dripping Spring, Barbarossa, Globe-Miami, and the Payson placers. Gold is associated with copper and silver lodes and  veins, and in porphyry copper deposits in the Globe-Miami district; with copper, lead, and silver in the Barnes district of the Dripping Spring Mountains and in ore in the Payson district. Silver occurs in the Globe district as minute flakes in calcite at the Continental mine, and also forms stout wires in the oxidized ore of the Old Dominion mine. Fine specimens are reported in placers about four miles north of Globe. At Richmond Basin, silver is one of the chief ore minerals and is found in large masses. At Payson, wire silver occurs in the oxidized ore of the Silver Butte mine.

Graham County in southeastern Arizona includes gold in the Rattlesnake district of the Galiuro Mountains; and in the Aravaipa and Stanley districts of the Pifialeno Mountains. Some gold is reported in the Gila Mountains and the Santa Teresa Mountains. Silver is reported at the La Clede mine in the Aravaipa district.

Greenlee County to the east of Graham County, has some gold associated with copper and silver ore in porphyry copper and in veins at the Clifton-Morenci district. Some gold placers also occur along San Francisco and Chase creeks and some interesting veins are located in the Ash Peak district. 

Gold in Maricopa County on the central part of Arizona, occurs with lead and silver in the Vulture and Cave Creek districts. Some gold is reported in the Phoenix and Bighorn Mountains. Some placer gold is described at Vulture, San Domingo, and Hassayampa, and silver is associated with granitic pegmatites in the White Picacho District.

Crustiform gold-bearing vein at the Gold
Road mine, San Francisco district

Mohave County lies in the northwestern corner of Arizona. In this county, gold veins are found in the San Francisco and Katherine districts in the Black Mountains, as well as in the Cerbat, Chloride, Stockton Hill and Mineral Park districts of the Cerbat Mountains. Examine Google Earth and search for "Oatman, Arizona", to get a view of the San Francisco district - there are literally hundreds of mines, prospects and veins in the area. Two mines are currently mining gold, the Gold Road mine, and the Moss mine, both located north of Oatman.

Gold occurs with silver in the Maynard district of the Hualpai Mountains and is also found in the Gold basin district. Gold is described in placers referred to at the Gold Basin, Chemehuevis, Lewis, Wright Creek, Lookout, and Silver Creek placers.  

Silver is found in masses several pounds weight in the deeper workings of the Distaff mine in the Cerbat Range; it occurs in the Lucky Boy and Samoa mines in the Chloride district; and is also found in the Golden Bee and Queen Bee mines of the Mineral Park district. Silver is found in solid chunks and masses of wire in the Banner group of the Stockton Hills district, and found in the Tennessee-Schuylkill mine of the Wallapai district.

In Pima County along the Mexican border, primary gold is found in the copper and silver in the Ajo district and the precious metals is also found in the Baboquivari Mountains. Gold is found with copper, lead and silver in the Comobabi and Empire mountains, and placer gold occurs at Greaterville, Quijotoa, Papago, and Horseshoe Basin districts. Less important are the Las Guijas, Old Baldy, Baboquivari, Armagosa and Alder Canyon placers. In 1924, an 11-troy-ounce gold nugget was recovered from the Greaterville placers. Silver occurs with chalcocite and cerargyrite at the Apache property in the Tortolita Mountains. The precious metal occurs with stromeyerite and tetrahedrite at the Cerro Colorado mine, in the Cerro Colorado range.

In Pinal County in southern Arizona, gold occurs with the copper, silver lead ores of the Superior and Ray districts; and is found in the Mammoth district. Gold occurs with copper and silver in the Casa Grande district. Gold is found in the Goldfield district of the Goldfield Mountains. Gold is reported in placers at the Canada del Oro deposit. 

Silver was found as magnificent crystallized and wire specimens at the Silver King mine and occurs in the upper parts of the Resolution (Magma) mine of the Superior district in the Galiuro Mountains. Silver is also reported as wire silver in small cavities the Little Treasure, and Adjust mines of the Saddle Mountain district. 

Santa Cruz County along the Mexican border, primary gold is found with lead, silver and copper ore in the Oro Blanco Mountains, and reported in the nearby Santa Rita Mountains and Patagonia Mountains. Gold placers are reported at Oro Blanco, Mowry, Harshaw, Tyndall, Nogales, and Palmetto. Silver deposits are found at the Domino mine of the Palmetto district of the Patagonia Mountains with crystallized cerussite and wulfenite. The precious metal is found with tetrahedrite at the Worlds Fair mine of the Harshaw district. Silver is also described as small crystals surrounded by magnetite in diorite on the southern slopes of the Santa Rita Mountains.

Highwall of the United Verde mine at Jerome

In Yavapai County near the center of the state, gold is found in the Verde district in massive volcanogenic sulfide deposits containing copper, silver, gold and zine ore. The United Verde mine and United Verde Extension mines were major mines that produced very rich massive sulfide deposits, but the mines left behind an unknown amount of low-grade ore. Gold is also found with lead-silver ores the Bradshaw Mountains at the Big Bug, Peck, Walker, and Tiger districts and in the Hassayampa and Black Canyon districts, in the Pine Grove and Agua Fria districts; and found with copper-silver ore in the Groom Creek, Turkey Creek, Bradshaw, and Tip Top districts. 

In the Eureka district of the Santa Maria Mountains, gold is found with copper, silver, and lead. In the Martinez district, it is found in the Date Creek Mountains and gold is found in the Black Rock district of the Wickenburg Mountains. The precious metals is also described in the Plomosa, Sheep Tanks, Dome Rock, Laguna, Trigo, and Gila Bend Mountains. Gold placers are found at Weaver Creek, Rich Hill, Lynx Creek, Big Bug, Minnehaha, Hassayampa, Groom Creek, Copper Basin, Placerita, and in the Black Canyon district. Many smaller placers are also reported. A 8.7-troy-ounce nugget was found on Weaver Creek in 1930, and in 1932 to 1933, several nuggets up to more than 3 ounces were recovered from the same area. 

Silver is described in a thin high-grade layer above the massive sulfide at the United Verde mine. It is found at several properties with argentite and cerargyrite at the Dos Oris mine in the Hassayampa district; as wire silver in cavities with argentite at the Arizona-National mine, Big Bug district; it is found with cerargyrite at the Goodwin properties of the Turkey Creek district; it occurs with proustite at the Thunderbolt mine in the Black Canyon district, and found with ruby silver and cerargyrite at the Tip Top mine in the Tip Top district. Silver is also reported at the Monte Cristo mine and found with niccolite and chloanthite in rich primary ore in the Wickenburg Mountains.

In Yuma County gold occurs with silver in the Kofa and Gila mountains. In the Harquahala Mountains, the precious metal is found with copper and lead. In the Cienega district of the Williams Mountains, gold occurs with copper. In the Castle Dome district of the Castle Dome Mountains, gold is found in lead-silver ore. In Yuma County, placer gold is found at La Paz, Gila City (Dome), Plomosa, La Cholla, Oro Fino, Laguna, Castle Dome, and Kofa districts. Less important are the Muggins, Trigo, and Harquahala placers.

The chemical symbol used for silver is Ag. Silver occurs as silver-white metal that is commonly tarnished gray to black. The native metal is opaque, sectile, ductile and malleable with hackly fracture. It is soft (H = 2.5-3), with high specific gravity (G =10.1-11.1) and crystallizes in the isometric, hexoctahedral crystal system. Crystals are typically malformed, acicular, reticulated, or dendritic. It commonly occurs as grains, plates, or scales. Silver is a common secondary mineral found in the upper portions of silver-bearing deposits, or in the zone of sulfide enrichment with chalcocite. Less commonly, silver is primary, disseminated in galena or in tetrahedrite.

Gold and Agates in the Payson Mining District, Arizona

Arizona is underlain by a Proterozoic geological basement, with the oldest rocks in this basement dating around 1.8 billion years old. This basement rock in Arizona, is overlain by younger sedimentary and volcanic rock. Arizona has many giant base metal deposits containing copper, lead, zinc, molybdenum, gold, silver and other metals that are classified as porphyry copper deposits, some massive sulfide deposits with copper, zinc, gold and silver, and scattered gold and silver veins and a few disseminated gold deposits along with lapidary to near gem deposits. Coal, oil, gas, and uranium occur in norther Arizona within the Colorado Plateau; whereas, the porphyry copper, massive sulfide, and lode gold deposits are found south of the Plateau.

The Payson Mining district (Green Valley district) is located in central Arizona, immediately south of Payson in the foothills of the Mazatzal Mountains. Geographically, this area is part of the central highlands between the Colorado Plateau to the north, which the southern extent is marked by the Mogollon Escarpment just a few miles north of Payson; and the Basin and Range marked by a series of distinct basins and ranges several miles south of Payson. 

Payson is reached by driving northeast along Highway 87-N (Beeline Highway) from the east valley of Phoenix. The Green Valley district is underlain by the Payson Ophiolite, a sequence of Precambrian rocks that date at 1.73 Ga that include volcanics, sheeted dike swarms, diorite, gabbro and tonalite. These lie on a 1.75 billion year old basement complex formed of granitic rocks that include felsic volcanics (igneous rocks rich in quartz and feldspar such as rhyolite) and volcaniclastic rocks. Ophiolites are chunks of the earth’s oceanic crust and underlying upper mantle that consist mainly of mafic igneous rocks (rocks rich in magnesium and iron such as basalt and gabbro) that have been uplifted above sea level in the geological past and emplaced in continental rocks. And yes, Arizona was under the ocean in the past as the continents drifted around the hemisphere.

The earliest report of gold in the district 

was 1875, which was followed by more discoveries over the next few years. The discovery of rich, free-milling gold-quartz veins resulted in an influx of a few hundred miners and prospectors. However, veins in the district were limited in size and the easily recoverable gold in the oxidized portions of the veins gave way to refractory, low-grade, sulfide-bearing quartz below the water table at depths less than 200 feet. Thus, no major mines developed and production records were not kept. Even so, both lode and placer gold were found.

The district is highly fractured and faulted and some fissures provided pathways for gold-quartz vein injections: many of the veins strike N15^oW to N65^oW and dip northeast. If you examine the area immediately southwest of Payson on Google Earth near the Delaware and Little Maude mines (map numbers 11 and 12, see below) you will see dozens of linear drainages that are structurally controlled by fractures and faults: most trend N70^oW to N35^oE. Similar distinct polygonal fractures are seen throughout the district and most intersect at right to near right angles, others produce rhombohedral fracture sets. Examine the area around 34°11'15"N; 111°22’30”W on Google Earth by first searching for ‘Payson, AZ’ and then search for matching GPS coordinates at the bottom of the Google Earth page to view many of these fracture-controlled, linear drainages.

In the 19th century, visible gold was found in veins at the Gowan, Oxbow, Golden Wonder and Zulu mines, and detrital (placer) gold was found downslope from the Oxbow mine four miles south of Payson. The placer gold included minute flakes and flat nuggets up to 0.25 inch long. 

Minor deposits of copper and silver were also found. Where found, wire and horn silver occurred in the oxidized part of the vein at the Silver Butte mine. The silver was associated with galena (lead-sulfide) and tetrahedrite (copper-iron-antimony-sulfide). Chalcopyrite (bronze metallic copper-pyrite) was also found at both Silver Butte and also at Bishops Knoll south of Payson, where some tetrahedrite, bornite (iridescent blue to lavender copper-iron-sulfide), covellite (iridescent blue copper-sulfide), chalcocite (black copper-sulfide), malachite (green copper-carbonate-hydroxide), azurite (blue copper-carbonate-hydroxide), chrysocolla (blue hydrated-copper-polysilicate) and dioptase (emerald-green copper-cyclosilicate) were described. Copper in the Green Valley deposits included lenses of tetrahedrite and some disseminated chalcopyrite and bornite in greenstones, and also disseminated pyrite, chalcopyrite and chalcocite in schist and mafic (gabbro and diorite) dikes.

Most gold-bearing quartz veins found in the district were fracture fillings in faults enclosed by crushed quartz zones along their margins. Since the host rocks were often extensively weathered, portions of the veins stood out as positive, resistant, outcrops. The gold-bearing veins ranged from a few inches wide to the vein at the Gowan mine that was as much as 12 feet wide. 

Gold was found associated with hematite and limonite in the oxidized portions of the veins. Below the water table, visible gold was absent and the gold values were lower and the precious metal appeared to be hidden in pyrite and chalcopyrite. Above the water table, free milling gold was found suggesting that the precious metal was tied up in the sulfides. 

Further evidence was provided by some vein samples that were described to contain tiny gold flakes in secondary hematite and limonite in quartz above the water table. Additionally, limonite pseudomorphs after pyrite were identified at the Oxbow mine. It was noted by miners that higher gold values correlated with higher limonite and hematite. 

At the Golden Wonder mine, some relatively recent explorers suggested that some of the gold was associated with high bismuth and tellurium content possibly indicating some gold was hosted by tellurium minerals (i.e., calaverite, petzite, or sylvanite) and possibly native bismuth.

Below the water table veins with pyrite and chalcopyrite typically assayed less than 1 opt Au (ounce per tonne gold). In the oxidized vein above the water table at the Oxbow mine, samples yielded 0.24 to 3.87 opt Au, and values at the Gowan vein above the water table were as high as 4.85 opt Au. Most host rocks were described as diorite altered to chlorite, sericite and secondary quartz over a width of several feet on either side of the veins.

General location map of the Green Valley district, Payson, Arizona, and mines including (1) Oxbox & nearby Midget, (2) Zulu, (3) Golden Wonder, (4) Payrock, (5) Maggie, (6) Callahan, (7) Silver King, (8) Summit, (9) Excursion, (10) Little Green, (11) Delaware, (12) Little Maude, (13) Single Standard, (14) Rock Ford, (15) Bishops Knoll, (16) White Mountain, (17) Crackerjack. The blue line marks the approximate outline of the Payson ophiolite complex.

There are several mines and prospects in the district. Some of these include Bishop's Knoll, Callahan (34°12'21"N; 111°22’55”W), Crackerjack, Delaware (34°10'49"N; 111°22’20”W), Eighty-five, Excursion, Gowan, Gold Rock, Golden Wonder, Lincoln, Little Green (34°11'11"N; 111°23’48"W), Little Maude (34°10'41"N; 111°22’41”W), Maggie, Mankin, Midget (34°9'48"N; 111°21’32”W), Oxbow, Payrock (34°12'40"N; 111°22’5”W), Rocky Ford (34°12'1"N; 111°22’18”W), Silver Butte, Silver King (34°13'34"N; 111°21’45"W), Single Standard (34°11'48"N; 111°22’8”W), Summit, Thompson, Zulu, and White Mountain (34°16'3"N; 111°24’12"W). A few properties appear to have been prospected over relatively large areas since the second world war such as the Golden Wonder, Maggie, Oxbow, and Zulu. These, in particular, should be examined for large tonnage gold mineralization. And these and other veins could provide opportunities for nugget hunters as well as for detrital gold downslope from the veins.

Placers are uncommon due to a lack of active streams. Some placer gold was recovered in drainages below the Oxbow mine during the rainy season when surface water was available. Much of the gold was found in surface gravel, but in 1939, placer gold was described in deeper gravels in an old channel unrelated to the current stream channel.

Some mined ore was hauled to the nearby Verde River where the gold was recovered by amalgamation in arrastra mills and later in stamp mills. And some attractive agates and chalcedony were also reported in the area including banded agate (34°12’45''N, 111°22’13’’W) and fire agate (34°12’40''N, 111°13’2’'W). 

Crackerjack prospect. SW¼NE¼ section 22, T11N, R9E (34°17'4"N; 111°25’18”W). The Crackerjack was a former underground copper-silver-lead-gold prospect located about 0.75 mile south of Cracker Jack Mesa on National Forest land (map number 17). The property was also known as the Copper King. Mineralization was found in a 3- to 5-foot-wide vein with lenses cut by cross fractures. The mine workings included a 350-foot tunnel on the vein about 150 feet down from the hill top, and a second tunnel was dug into the footwall of the vein. A 45-foot deep shaft was sunk at the top of the hill.

The fissure vein strikes N80^oW and dips 80^oN and is hosted by Precambrian felsic rock that shows moderate chlorite alteration near the vein. The Crackerjack mine lies along a fault zone separating Larsen Spring Formation (1.75 Ga) felsic volcanics and volcaniclastics from much younger Tertiary rocks to the southwest. Gold, malachite, brochantite (green copper-sulfate), chalcopyrite, cuprite (red copper-oxide), chalcocite, bornite, quartz and limonite were reported on the mine dump. Two ore cars shipped from the property contained an average of 7.7% Cu and 8.7% Cu.

Gowan (Excursion?) mine. N/2 section 23, T10N, R9E (34°11’50”N; 111°24’12”W) (map number 9). Eleven patented claims were granted for this property (patented claims means that the property is privately owned). The footwall of the Gowen vein was described as altered hornblende diorite intruded by porphyry granite. Sycamore Creek sandstone (Devonian) was reported to sit on the igneous rocks, and was down-dropped along a fault. The vein strikes N15^oW and dips 32^oNE and has a maximum width of 12 feet. Some free gold was reported in the vein. 

The property was at one time operated by the Excursion mining company and included several thousand feet of development work. The gold ore was processed using a 10 stamp mill and was free milling and reported to average about 2.5 opt Au. Cuts on the surface and in outcrop show the vein to be continuous for at least 900 feet with an average width of 3 feet.

Golden Wonder mine. Center section 18, T10N, R10E (34°12'41"N; 111°22’19”W) (map number 3 between 4 and 5). This property (also known as the Eighty-Five and Gold Rock) is underlain by altered hornblende diorite and gabbro. A quartz vein strikes northwest and has a near vertical dip with a maximum width of 4 feet. The oxidized portion of the vein was mined for free milling gold, but was not minable below the water table because the vein had lower ore value.

In a press release (1/30/2013), Golden Wonder Mine, LLC, reported excavation of 90,000 yds³ of ore on the property and reported assays of 0.13, 2.6, 12.4 to 100 opt Au. The company indicated gold was closely associated with higher bismuth and tellurium content at depth.

The mine had been initially developed by several hundred feet of underground workings and low grade ore was reportedly stored in the old stopes. Mine production was estimated at about 5,000 ounces of free-milling gold by 1909. The nearby Maggie prospect lies a short distance west and the Payrock a short distance east (on strike) suggesting the vein(s) could have a strike length as much as 0.6 mile. Part of the Golden Wonder was mined by open cut and more recent trenching is apparent on aerial photography.

Maggie Vein. W/2 section 18, T10N, R10E (34°12’32”N; 111°22’34”W) (map number 5). This is likely the southwestern extension of the Golden Wonder mine. A 125-foot ore shoot was explored along a 4-foot-wide vein. Two samples from a stope averaged 1.9 opt Au over a 1-foot width.

Oxbow Mine. NW section 32, T10N, R10E (34°10'5"N; 111°21’16”W). The Oxbow lies west of Oxbow Hill and about a mile west of Highway 87 (map number 1). The property lies on two patented claims that enclose a vein within the Payson Ophiolite. The property includes a highly altered rhyolite dike and some fine-grained diorite dikes. 

The Oxbow vein occupies a roughly N-S trending fault fissure that has curved geometry, similar to an oxbow in a stream. At the main portal, the vein is 4 feet wide and swells to 6 feet: wider portions of the vein have higher gold values. Where the vein narrowed to a few inches, the fracture was occupied by inward projecting quartz crystals. Adjacent to the vein, quartz stringers projected into the hanging wall. The mined ore was reported to contain as much as 1.7 to 2.25 opt Au. 

The water table was intersected at 175 feet below the collar of the two compartment shaft sunk to a depth of 176 feet in 1925. In addition, more than 500 feet of tunnel was dug from an adit. According to mindat.org, the property has a mineralized zone that is 1,950 feet long, by 5.9 feet wide and is 515 feet thick. The vein has a 45 to 85^oW dip, and at least 5 ore shoots were recognized. Numerous cross veinlets were intersected during past exploration and some placer gold was found on the property. Fluorspar was also described on the property. 

Single Standard mine. Center section 19, T10N, R10E (34°11’48"N; 111°22’8”W) (map number 13). According to topographic maps, the Single Standard is located south of the Golden Wonder mine; however, Lausen and Wilson (1925) indicated the mine was a mile to the west at the approximate location of the Callahan mine (34°12'21"N; 111°22’55”W). The vein cuts the host rock (diorite) which itself is cut by fine-grained diorite dikes. The vein strikes N65^oW and dips 55^oNE. Where the vein outcrops it is only about 12 inches wide and consists of massive quartz with some hematite and limonite. 

Summit Mine. E/2 SE section 36, T11N, R9E (34°15’1”N; 111°22’39”W). The Summit vein (map number 8) was discovered in 1881 and a patent was granted on the property in 1890. It was reported in 1925: “considerable ore is said to have been produced and a large dump is stated to average $7 in gold”. In 1925, gold prices were $20.67/ounce, thus this would be equivalent to 0.34 opt Au. 

In the 1940s, work continued on the mine. It was reported that the main vein had a strike trend of N21^oW and consisted of quartz with schist gangue (Payson Roundup, 2009).

Zulu mine. N/2 section 1, T9N, R9E (34° 9'32"N; 111°23’5”W). The Zulu property (map number 2) is underlain by rocks of the Payson Ophiolite reported as diorite that was intruded by granite porphyry dikes and fine-grained diorite dikes. A rich, 20-inch wide ore shoot was found in a narrow quartz vein that was explored in a mine shaft. Numerous quartz veinlets extended into the wall rock (Lausen and Wilson, 1925) suggesting a possibility for low-grade gold mineralization surrounding the vein. 

Aerial photos show the property was extensively prospected by dozer cuts over an area of 0.35 by 0.65 mile. This may suggest past operators may have found gold anomalies in the altered wall rock, or that they were searching for hidden veins. 

Mineralization was described to include a 3,900 foot long and 19.5 foot wide zone containing a gold-silver-quartz vein with stingers of ore and barite gangue in fractures. Other reports suggested two ore shoots were intersected at depth that were separated by altered granite in a ore zone about 30 feet wide.

Initially, the mine was developed by a 200-foot-deep two compartment shaft. Later work included minor ore recovery in the 1950s and some heap leaching in 1981 and 1982. Reported assays in 1939 ranged from 0.02 opt Au to 5.94 opt Au. The latter sample was taken in the vein at the 150-foot mine level in a 9-foot wide vein.

In summary, the Green Valley district south of Payson lies within favorable host rocks for gold mineralization and offers potential opportunities for nugget hunters near veins that yielded free milling gold. Past erosion and flash floods likely carried some gold downslope from the veins into the surrounding drainages.

Some deposits likely contained large areas of low-grade gold mineralization that may have been overlooked and little ore was tested below the water table. With the numerous fractures in the area, it is likely some veins have been missed in the past.

Finally, ophiolites are known to host certain types of mineral deposits including copper and gold. For instance, some ophiolites contain platinum-group metals, chromium, manganese, titanium, cobalt, nickel and other metals of interest, but there does not seem to be any reports of prospectors searching for these types of mineral deposits in the past.

References

Arizona Geological Survey, 1986, Miscellaneous reports on the Crackerjack and other properties in the Payson district: May 7, 1986, http://docs.azgs.az.gov/OnlineAccessMineFiles/C-F/CrackerjackGila511a.pdf. ). 

Hedburg, Ed, 1909, The Greens Valley Mining District: Ming World, December, 25, p. 1245-1256. 

Johnson, M.G., 1972, Placer gold deposits of Arizona: US Geological Survey Bulletin 1355, 103 p. 

Kusky, T.M, 2004, Precambrian Ophiolites and Related Rocks: Developments in Precambrian Geology 13, Elsevier, 772 p.

Lausen, C., and Wilson, E.D., 1925, Gold and copper deposits near Payson, Arizona: University of Arizona, Arizona Bureau of Mines Bulletin 120, no.4, 43 p.

Minedat dot org - various mineral reports on the internet.

Peterson, J.A., 1984, Metallogenic maps of the ophiolite belts of the western United States: US Geological Survey Misc Investigations Series Map I-1506. 

Rhodimer, T., 1939, Assay report on the Zulu mine dated Dec. 9, 1939.

Order L-208, A Gold Mine Waiting to be Mined Again

Ever hear anything about the War Minerals Board Order L-208? If you haven't, and you are a gold prospector, it is something you will want to learn about, because it can lead you to a good, abandoned gold mine!

It turns out that during world war II, the US government ordered all non-essential mines (i.e., gold mines) to close and focus all efforts on the war. After the war, many of these commercial gold mines that were producing gold at a price of $35.50 per ounce when closed during the war, never reopened because many did not come back from the war, lots of the closed mines and mills fell into disrepair, many flooded, and after the war, our country focused on infrastructure, rather than gold. 

So, imagine you found one of these old mines in Arizona. Today's gold price (2/23/2022), according to the blogspot "Searching for Gold" is $1,908 per ounce, or nearly 54 times higher than it was when during World War II. So, nearly every L-208 mine likely is commercial at todays price! 

These and other mines are described, in a new book available on Amazon entitled, "Gold in Arizona". And there are many other gold anomalies described in the book, including those associated with detachment faults. So, the book provides information on dozens of detachment faults and prospects in these unusual types of faults that run from the northwestern part of the state to the southeastern part of the state.

Kindle version on Amazon

It took a few years, but finally, Gold in Arizona - A Prospectors Guide was published in December, 2019. After researching gold deposits in Arizona, it is clear to me that Arizona is not only the copper state, but would better be known as the Copper-Silver-Gold state. 

Hard to believe, but Arizona has produced much more than 500,000,000 ounces of silver and 16,000,000 ounces of gold along with all of its copper, zinc, lead and turquoise. So, in this book, many of the old mining districts are described with many of the mines. And, there are many deposits that have been overlooked, and many that have only been partially prospected.

Ezra 8:27

United Verde Mines, Jerome (Verde) district, Arizona

Black Smoker from the bottom of the ocean
in Arizona! Yes, when this hydrothermal vent
was active more than 1.7 billion years ago, 
Arizona sat at the bottom of an ancient ocean
where deep hot-springs emitted gas and sulfides
from such vents and produced one of the greatest
massive sulfide deposits ever found, and high
and dry, Jerome, Arizona.

From Flagstaff, we decided to take a detour to the Verde district: a highly mineralized area. The district is 90 miles north of Phoenix along the edge of the Black Hills in Yavapai County, central Arizona and locally referred to as the Jerome district. It encloses a 30 mi2 mineralized terrain with two major mines along the northern edge of the town of Jerome. The two principal mines in the district are the United Verde and United Verde Extension. To get to the district, drive south on Highway 89A from Flagstaff. You can also visit the town on your computer by searching for “Jerome, AZ” with Google Earth.

On the northwestern edge of Jerome is a large, partially reclaimed, open pit mine that is part of the United Verde mine. The rest of the mine lies underground and inclues 81 miles of tunnels and shafts hidden beneath the open pit, Cleopatra Hill and the adjacent valley. A large active quarry is visible near the northeastern edge of town that is actually the Clarkdale quarry and cement plant, which has little to do with the base metal mines. Evidence of the old smelter works is visible further east near the Verde River and expressed as black slag with some old buildings and foundations.

If you are familiar with gossans, you should be able to trace an extensive belt of rusty-colored rocks on aerial photographs on Google Earth. I followed the gossan 7 miles north of the United Verde Mine, and another 7 miles south! Such an extensive gossan likely hides ‘blind deposits’! My experience is that for every mineral deposit found on the surface, there likely is many more hidden at depth in the immediate area (and who knows how many lie hidden under the adjacent valley sediments). And like most mines reported to have been mined out, the United Verde is far from being mined out. In fact, the US Geological Survey reported at least twice as much unmined ore remains in place as was mined in the past. Actually, it is extremely rare for a major mineral deposit to be mined out as most productive mines terminate operations because of declining economics as prices and markets fall during bad times.

Jerome, Arizona, looking towards Cleopatra Hill. The hill with the ‘J’ is Cleopatra Hill and the 

United Verde open pit is the mine dump seen in distance to the right of the J between the two 

prominent hills. The tops of two head frames of the United Verde Extension mine are visible in the

foreground.

When I was a student in geology, the Verde district was considered as an exploration model for ‘submarine volcanogenic massive sulfide deposits’. One geological dictionary defines massive sulfide very simply as: “an unusually large deposit of sulfide minerals”. But there is more to massive sulfide deposits.

Massive sulfides bring thoughts of copper and zinc to geologists. And for myself, I also think of precious metals. Sulfide minerals in many of these can enclose significant amounts of gold and silver. So much silver was found associated with these deposits at Jerome that the recovered silver essentially paid for the mining operations. And many banded cherts (known as exhalites) associated with ‘submarine volcanogenic massive sulfides’ (VMS) contain anomalous gold.

VMS refers to a type of mineralization with zones of massive (as well as disseminated) sulfide minerals that were deposited beneath the ocean in hydrothermal vents including white and black smokers. Over geological time, many of these VMS deposits now lie on dry land due to tectonic forces while modern deposits continue to form under the ocean. Where found, VMS deposits are hosted in rocks 3.55 billion years old to the present and may even include deposits with a hundred million tons of ore rich in gold, silver, copper, zinc, lead and other metals.

White smoker sinter column. White smokers precipitate in hydrothermal vents and often 

have auriferous silica. Black smokers are sulfide rich and associated with higher 

geothermal temperatures (specimen from the United Verde mine, and on display at the 

Douglas Museum in Jerome).

VMS deposits have distinct rocks such as volcaniclastics (breccias) that represent very active submarine vents. Some of these are so distinct that one Canadian geologist dubbed them ‘mill rock’ years ago because he noticed there were operating mills and mines adjacent to many of these.

In addition to volcaniclastics (mill rock), siliceous mounds or chimneys are formed by submarine fumaroles that are referred to as black and white smokers. Other distinct rocks include layered stratiform rock known as exhalites that formed during eruption of heterogeneous volcanic material in sea water: the layering was produced by sea water naturally separating minerals by specific gravity as they slowly settled in the ocean water.

The host rocks for the VMS deposits in Jerome are 1.7 billion years old and similar in age to VMS deposits discovered in Colorado and Wyoming in 1979 and the early 1980s. You might be wondering what submarine VMS deposits are doing in the dry deserts of Arizona and high mountains of Colorado and Wyoming? In the geological past, these were accreted to continents and buried by tectonic forces related to continental drift. After millions of years of erosion following mountain uplift, some have been exposed at the surface, while many more remain hidden and undiscovered. Those hidden at depth are referred to as ‘blind’ deposits. Still others continue to form in the oceans, particularly along active volcanic island chains (such as Japan) and along spreading centers such as the Mid-Atlantic Ridge.

When I was the Senior Economic Geologist and Deputy Director at the Wyoming Geological Survey, Conoco Minerals discovered VMS deposits in 1979 in the Sierra Madre Mountains west of Saratoga. But few have heard of these deposits because of the US Forest Service. Those that were found near the old Itmay mine, not far from the famous Ferris-Haggarty mine, were withdrawn from public use. Other VMS deposits were soon found in Colorado and Wyoming. The discoveries sent shock waves through the Forest Service which had little taste for mining; and the agency hurried to withdraw the new discoveries until all, or portions or most VMS deposits fell within or adjacent to the withdrawals effectively locking out mining companies and prospectors from public land.

Much of this region in Colorado and Wyoming was known as the Grand Encampment district, which in the 19th century, prior to government interference, was a major base metal district. But because of the withdrawals, no jobs were created because of Conoco’s discoveries, no valuable metals were mined, and the US continued out-sourcing jobs and importing base metals.

Today, the Verde district is idle and the town of Jerome is a tourist attraction built on the flank of Cleopatra Hill which rises more than 6,000 feet above sea level. Some buildings in Jerome were constructed on the Precambrian rock that forms Cleopatra Hill, while the rest of the town slopes downward on Tertiary to Recent fanglomerates and landslide debris. The landslide has been a historical problem and periodically slides following periods of high runoff. At the base of the slope, the surface flattens eastward to the Verde River valley at Clarkdale and Cottonwood 4 to 5 miles east of Jerome at an elevation of 3,300 feet.

Production

Jerome was a major copper-gold-silver-zinc-lead district. According to the Arizona Department of Mines and Mineral Resources (2007), 48 of 70 known VMS deposits found in Arizona have produced ore - all of which are Precambrian age (1.7 to 1.8 billion years old). Production from these totaled more than 55 million tons. Most of these deposits are steeply plunging and deformed, such as the United Verde, which has been described as a rod-like ore body or pipe located within an axis of a major, steeply-plunging, fold.

About 98% of the past production in the Verde district was from the United Verde and United Verde Extension mines. Even though mining ceased in 1953, there is evidence that the miners left behind considerable ore. The district was considered to be a copper district, but at today’s metal prices, the district would be classified as a copper-gold-silver-zinc district. Considerable copper, gold, silver with some zinc and small amounts of lead were recovered from the two principal mines.

In 1989, the US Geological Survey indicated records from Phelps Dodge showed production from the United Verde Mine from 1884 to 1975 amounted to more than 2,926,900,000 pounds ($10.1 billion at 2012 prices) of copper, 97,891,000 pounds ($82 million) of zinc, 459,000 pounds ($390 thousand) of lead, 49,603,000 troy ounces ($1.4 billion) of silver, and 1,354,200 troy ounces of gold. Koschmann and Bergendahl of the US Geological Survey reported gold production was even higher at 1,571,000 ounces ($2.5 billion) over the lifetime of the district. Based on statistics from the U.S. Geological Survey and Phelps Dodge, the United Verde produced $14.8 billion in metals at 2012 prices.

High wall of the United Verde open pit mine with head frames in foreground. Note large distinct, rusty gossan produced by oxidation of massive sulfides in the background. The massive sulfides were so rich that they actually ignited and burned underground for many years!

History

The cupriferous gossan exposed at the surface at Jerome was found by prehistoric tribes hundreds of years ago. In 1875, the U.S. Army rediscovered the gossan and in the following year (1876) prospectors rushed to the district to claim the discovery. By 1882, much of the minable land had been consolidated by the newly formed United Verde Copper Company which began extracting near-surface oxidized and supergene enriched copper ore rich in gold and silver. Underground mining began in 1883, and open pit mining was initiated in 1920.

A second company, (United Verde Extension [UVX]), was organized in 1899 to search for a suggested, down-faulted continuation of the United Verde massive sulfide. UVX began searching southwest and east of the United Verde property. Their efforts were fruitless until they were on the verge of bankruptcy in 1914, when a drift driven from a shaft east of the United Verde mine intersected bonanza grade ore rich in chalcocite on the 1,200 level. In 1916, another ‘blind’ deposit was found. The ore was so rich the company ended the year with a 74% profit after expenses. Later geological studies showed the UVX discoveries were not part of an off-set of the United Verde ore body, but instead completely separate, ‘blind’ ore bodies.

The UVX mine operated on a large scale until 1938 when much of its high-grade was mined out and operations ceased. The nearby United Verde mine continued mining. After 1931, much of their activity focused on open-pit mining. Depletion of ‘high-grade’ reserves finally forced the mine to close in 1953. This resulted in many people reporting that the deposit was mined out. However, the operations left behind a giant, low-grade, ore deposit and who knows how many ‘blind’ deposits.

Geology

The VMS erupted as hot, sulfide-rich material into cool water resulting in precipitation on the ocean floor 1.7 billion years ago. The Verde VMS lies at the top of a submarine rhyolite dome and flow breccia known as the Cleopatra Member of the Deception Rhyolite. The ore is zoned and capped by chert and siliceous massive sulfide that grades down into pyrite-rich massive sulfide, zinc-rich massive sulfide, copper-zinc-rich massive sulfide, chloritic stringer ore, and chloritized quartz porphyry ore. Gold is found throughout but is in greater concentrations at the stratigraphic top (siliceous massive sulfide and chert ore).

Gold is in greater concentrations in chert. For instance, on the 4500-foot level, the black schist yielded 0.002 opt Au and 0.71 opt Ag. In chert near the surface, the ore yielded values as high as 0.12 opt Au and 4 opt Ag (60 times more gold). On the 700-foot level, the massive sulfide averaged 10 times more gold than the black schist. A positive correlation of gold with higher zinc content was also recognized by the US Geological Survey. This is important as much zinc ore was not mined.

Sulfides are exposed at the surface down to the 4500-foot mine level, but in the geological past, the ore also extended upwards to the base of the Cambrian Tapeats Sandstone indicating at least 350 feet of vertical column of massive sulfide was removed by erosion. With this much erosion, drainages down-slope from the massive sulfide should contain detrital gold, but I could not find any report suggesting that gold had been detected in the nearby drainages. Based on the mode of occurrence, the gold would likely be very fine grained.

Ore minerals in the massive sulfide in decreasing abundance included pyrite, sphalerite, chalcopyrite, bornite, arsenopyrite, galena, tennanite and gold (electrum). Much of the electrum is thought to be present as microscopic inclusions in sulfide minerals. Silver is present in the electrum and in late-stage tennanite (Cu12As4S13) in quartz carbonate veins and in carbonate rich massive sulfide ore. The tennanite also contains gold as microscopic inclusions.

The Verde was the largest known volcanogenic massive sulfide deposit in the US with 33 million tons of mined ore, and 50 to 70 million tons of low-grade ore left in place. It is also considered to be one of the largest in North America. The massive sulfide was steeply-dipping, irregular- to cylindrical-shaped ore body approximately 700 to 800 feet in diameter that extended 2,400 feet deep. The United Verde mine reached a depth of 3,515 feet and included eight shafts. According to the US Geological Survey, proximal ore recovered from the mine averaged 4.77% Cu, 0.046 opt Au, and 1.65 opt Ag. Zinc and lead were not recovered during much of the operations. Another blind ore body was found in the lower levels of the mine 500 feet northwest of the roots of the main deposit.

Anomalous gold was detected in the pyritic and sphalertic massive sulfides and the chert rich ore: chloritic host rocks are poor in gold. The zinc ore contained as much gold as the copper ore. And because only the high-grade copper-rich portion of the massive sulfide lens was mined, a very large tonnage of low-grade ore remains in place and it was estimated that at least 75% of the mineralized deposit remains unmined because it was too low-grade to mine (<2% Cu) under historical economics. The estimates suggest about 115,000,000 tons of low-grade massive sulfide ore and 38,000,000 tons of mineralized black schist remain in the mine with grades of 0.5 to 1% Cu, 2 to 4% Zn, 0.01 to 0.015 opt Au and 0.5 to 1.0 opt Ag. This zinc-rich deposit is estimated to have 400,000 troy ounces of gold.

At the United Verde Extension Mine, mineralization occurred in an elliptical ore body hosted by the Deception Rhyolite and Grapevine Gulch Formation. The main chalcocite ore body was found on the 1400-level and was 269 feet wide and 440 feet long on this level.

You may not appreciate this exhibit at the Audrey Head-frame Park in Jerome if you have.

a fear of heights. Sunlight is projected down the 1900-foot deep Audrey shaft so visitors can

see the depth of these mines. When I took this photo, I was standing on the plexiglass

covering the deep shaft.

The UVX mine produced 3,879,000 tons of ore that averaged 10.23% Cu, 0.039 opt Au, and 1.71 opt Ag. Ore minerals included chalcocite, cuprite, native copper, malachite, chrysocolla and azurite hosted by felsic fragmental rocks, massive rhyolite and quartz porphyry – all units of the Deception Rhyolite.

Part of the UVX operation was developed by the Haynes Shaft due west the United Verde open pit. This deposit was another blind ore body found at 2,500 feet below the surface. The UVX decided to explore the ground under the Haynes shaft by driving a tunnel at the 3,000 level. A drift was started in 1930 and reached the Haynes massive sulfide pipe in 1931.

The Haynes proximal pipe was a steeply-plunging massive sulfide. It extended a short distance above the 2700-level downward to an undetermined point between the 3450 and 3700 levels of the United Verde Mine. The Haynes haft was sunk to 700 feet between 1907 and 1911; subsequently deepened to 1,200 feet, with 1,700 feet of drifts and crosscuts on the 700 level and 700 feet on the 1200 level.

Gold Basin District, Arizona

Many dry gold placers are found along the eastern edge of the White Hills extending east to Hualapai Wash in Mohave County (T28 & 29N, R17 & 18W), NW Arizona. These are the Gold Basin placers. Search for "Gold Basin, AZ" on Google Earth, and hopefully, you will arrive in the middle of Gold Basin, a short distance east and south of the many dry gold placers known in this basin. 

The area lies south of Lake Mead, the Lake Mead Recreation area, and the Colorado River. The nearest communities are Meadview (36o00’00”N; 114o04’00”) and Dolan Springs (35o35’25”N; 114o16’25”W). Due to the large number of retirees and snowbirds in the region, each community is surrounded by suburbs.

The placers are dry placers in the desert, and these contain detrital gravels (1 to 5 feet thick) that mostly lie on hard, false, bedrock of consolidated gravel cemented by caliche - unfortunately, there is no shortage of caliche in Arizona. The overlying gold-bearing gravels are weakly mineralized with considerable black sand, quartz, and rock fragments of schist and gneiss eroded from the Precambrian terrain in the White Hills. 

Gold content of the placers is poor and may only be 0.03 to 0.04 ounce per cubic yard at best; while the underlying consolidated gravel remains mostly unexplored. Gold nuggets are rare. Some up to an ounce have been found with the largest only 4 to 5 ounces in weight. Much of the gold-bearing area is part of the White Mountains alluvial fan that extends from the eastern flank of the uplifted White Hills to Haulapai Wash to the east. The fan covers a surface area of 6 by 5 miles and you can drive to the area northward on the Pierce-Ferry highway (Road 25) through Dolan Springs. 

Lode gold was discovered in quartz veins in Precambrian rock in the 1870s. Placer gold from the veins was not found until the Great Depression. In 1932, W. E. Dunlop found gold in the dry gravel which attracted others. The amount of gold recovered by the prospectors was minor. Even experienced miners only made about $1 per day (1933 wages). And the total amount of reported gold recovered from the Gold Basin placers is only 415 ounces produced during the period of 1934-49. 

The gold-bearing gravels occur in arroyos and gulches at elevations of 3,300 to 2,900 feet. The gravels have medium-grained, angular schist and gneiss fragments with a minor amount of finely divided quartz. A small number of boulders are encountered that are generally less than 2 feet in diameter. The gold occurs as flour gold and less commonly as angular nuggets with some gold attached to black schist particles. The White Hills, which are made up of granitic, schistose, and volcanic rocks, contain many argentiferous and auriferous quartz veins that are the likely source for much of the Gold Basin gold (Wilson, 1981).

The gold placers have erratically distributed gold. In addition to dry placer mining, there is considerable prospecting with metal detectors. Some find gold, while others have found a bonus of meteorite fragments.