The GOLD HUNTER

The Search for Gold, Silver, Platinum Groups & Gemstones

GOLD IN ARIZONA

 

In 2006, I packed up and left God’s country for Arizona. God’s country? Why it’s Wyoming! However, my wife and others refer to the least populated state in the US with a four-letter word giving the erroneous impression that it belongs to Lucifer. The non-stop hurricane-force winds, cold, and weather suitable for an Eskimo drive people crazy; but others, thicken their blood, enjoy a little frost bite, and come to love the cowboy state. If you don’t believe me, ask all ten of us.

 

There are many interesting things about Wyoming besides Yellowstone, the Grand Tetons and crooked politics. No matter which direction you ride a bike there is always a head wind. If you play tennis outside and orient yourself properly, you don’t need a partner. In the fall, spring, winter, and most of the summer, you need a snow shovel and a putter to play golf on the less than crowded courses. So there are benefits.

It’s rumored that the Delaware Indians named ‘Wyoming’, in reference to mountains and valleys. But the Delaware Indians never made it to Wyoming - that's why they are called the 'Delaware Indians', so this may not be exactly right. Myself, I’m nearly 1/30th American Indian. So being a partial authority, I know Wyoming actually means ‘big wind’ in reference to non-stop winds and blowhard politicians.

I loved working in Wyoming. It was mostly unexplored for metals and gemstones when I arrived in 1976. Over three decades others and myself found hundreds of precious metal anomalies, colored gemstones and diamonds along with some base metals, rare earths and some of the oldest and youngest volcanic rocks in North America. Prior to 1976, few mountain ranges had been mapped geologically and essentially no gemstones were known in the state other than jade. It was a geologist’s dream! While most other geologists in the Geological Survey meditated (I think that’s what they were doing) or researched General George Custer, I spent years mapping old mining districts and loving every minute (except the days I buried vehicles in bogs). Today, Wyoming is known to have the most diversified assemblage of gemstones in the US (Hausel and Sutherland, 2000); and it will likely have its first lode gold mine in more than century by the end of the next decade in an area where I had discovered a gold district in the early 1980s (Hausel, 1996)! This fact alone is incredible based on the number of gold anomalies that were found in the state over the past 3 decades (Hausel, 1989; 1997). But based on the incredible drilling results and assays of Evolving Gold in this district, they could have another Cripple Creek!

I worked in this geologist’s Garden of Eden until 2005-06. After discovering possibly three of the largest colored gemstone deposits in the world (Hausel, 2005). More than a century later, I examined the hydrothermal alteration mineral assemblages surrounding the Copper King mine and drilling by various companies and the US Bureau of Mines identified a Proterozoic porphyry with a gold-copper resource of a million ounce equivalent. All within a mile of the purported salting scheme (Hausel, 1997) and nearly within view of Interstate 80. What is even more incredible is that this $1.4 billion dollar deposit is only 15 miles west of Cheyenne and sits within a giant field of cryptovolcanic structures that likely include many untested kimberlite (diamond) pipes.

By 2006, the Wyoming Geological Survey’s integrity had reached a low, like so many scientific agencies and universities recently influenced by politics. I was lucky - I had just enough time to retire and Aussie, Canadian and US diamond, gold, and base metal companies were knocking on my door.  So I answered.

My wife, bless her, couldn’t take another day in Wyoming, particularly after we had lost sight of the backyard in a snowstorm sometime in November. We hadn’t seen it for months. Where was Al Gore when you needed him? So, Sharon grabbed my ear lobe, and off we went to Gilbert, Arizona, one of the hottest places on earth. But now that I’ve been in Arizona for a few years, my blood is thinning - I can actually walk outside for a few minutes each summer. Arizona is as hot as … well you know. In Gilbert, you can cook an egg on the sidewalk any day of the year. On the brighter side, we do have Sheriff Joe, and there are many old mining districts in Arizona to explore (particularly if you are more heavily armed than Mexican drug cartels).

So we began investigating mining districts in Arizona and nearby states within the Basin and Range province. Just like I anticipated, there are many overlooked gold and copper deposits and anomalies. These will require reconnaissance prospecting, detailed geological mapping, sampling, and drilling, but if properly explored or prospected, Arizona could add a few more cash cows to their mine production.

If I were governor, I would look for ways to attract more prospectors, mining and manufacturing to Arizona. I would sit down with consultants with experience in Finland, Alberta and Quebec to see what these governments are doing to attract mining interest and investment and search for ways to re-industrialize Arizona (since the Feds are reluctant to create meaningful jobs), attempt to circumvent duplication of exploration permits and encourage industry to revitalize mills, smelters, and build factories to produce goods made in Arizona. I would initiate a program to provide grants to the unemployed who would like to take up serious prospecting. The heck with rebuilding roads: the more potholes in Phoenix’s highways, the better. It might slow traffic to a reasonable speed.

Arizona has always been a very important source for copper and other base metals and has produced significant amounts of gold and silver. Most of the easy deposits have been found, and there are likely many deposits hidden under our feet. Some anomalies suggest the presence of hidden gold and copper deposits including giant, copper-gold porphyries.

For those unfamiliar with porphyries, these are thought to represent root zones of old volcanoes or magma chambers. Rocks associated with porphyries include multiple granitic stocks (more specifically granodiorite, diorite, quartz monzonite, rhyolite, and andesite); some of which have porphyritic texture. A porphyritic rock is simply an igneous rock that has larger crystals (such as feldspar and quartz) dispersed throughout a finer grained rock matrix. When mineralized, porphyries may have disseminated sulfide blebs in rock matrix along with some mineralized fractures, veinlets and veins. When such mineralized rocks intrude reactive rocks such as limestone, the intruded rock is replaced by massive sulfides known as replacement deposits or skarns. Mineralized porphyries are also accompanied by high-grade veins, veinlet networks called ‘stockworks’ and mineralized breccia pipes. Thus when searching for porphyry deposits, one needs to become familiar with porphyritic texture, breccia pipes, mineral zonation and wallrock alteration.

Veins near mineralized porphyries contain copper and gold, further from the center the veins become enriched in zinc and copper or silver and lead. Wallrock alteration is likely to leave a normally white to pinkish igneous rock replaced by broad zones of greenish colored minerals (chlorite, epidote, calcite, etc) known as propylitic alteration. I mention this only because my neighbor across the street in Gilbert has his yard filled with large porpylitically altered boulders but unfortunately has no idea where they came from.

Veins provide good targets for prospectors as many have high gold and silver values. For example, a group of veins explored near the Kirwin porphyry by AMAX in the 1970s-80s in Wyoming, yielded channel samples with >50 ounces per ton (opt) silver, and a few that assayed >100 opt silver. What is amazing about these is they were taken at the mine face (the last place that was mined) indicating the miners walked away from economic silver and gold veins (Hausel, 1982)! But like nearly every place in Wyoming where someone made a discovery in the past 35 years, either the Federal or state government followed discoveries by withdrawing the property from exploration. If discovered on private property, the government worked with private groups to purchase the property and donate it to the government. This happened so often that it became absurd. As an example, one deposit I explored after receiving information from a local rock hound contained giant opals including the first fire and precious opals found in Wyoming (Hausel, 2005a). Following the announcement of the discovery, I was contacted by the Bureau of Land Management who demanded to know the location of the discovery so they could withdraw it to protect the rare flowers (yet they had no idea where it was located)!

Figure 1. Vein samples collected from the Kirwin district by Ora Rostad.

(a) Massive pyrite and chalcopyrite containing invisible gold with brecciated phyllically (potassium-enriched) altered lithic fragments.

 

(b) Oregon vein breccia sample from Galena Ridge.

 

 

 

 

 

(c) Massive pyrite - gold vein from the Pickwick vein (photos by the author).

 

 

Many veins and dikes associated with porphyry centers radiate outward. Even though porphyry deposits are considered low-grade and primarily mined by open pit, they often enclose a few $billion in metals including copper, gold, silver, lead, zinc, molybdenum, some gemstones and some rare metals. Porphyry deposits have distinct rock types, extensive wallrock alteration and mineralization which help the geologist and prospector to identify these. If you would like to see what several billion dollars look like, visit the Bingham copper mine west of Salt Lake City (Chenworth, 2010). This is a giant porphyry deposit mined for more than 100 years and is the largest open pit mine on earth.

According to historical reports, prospecting in Arizona began with Spanish and Mexican prospectors who searched for silver. However, they were unfortunate - they could only find gold and copper. Gold was discovered in 1774 in the Quijotoa Mountains (60 miles west of present day Tucson) by a Spanish priest. The gold occurred in gravel and in nearby veins associated with hematitic breccias. Following this discovery, gold was found in several districts over the next two centuries. Many of these are described by Wilson and others (1969) and Wilson (1981).

Many gold placers in Arizona are reported in fanglomerates which lie within and on pediment surfaces high and dry at the base of mountains or hills. Often, limited placer gold is also found in adjacent gulches down-slope from these pediments. Similar to Australia, active stream placers are rare in Arizona because of the lack of perennial streams. Gold in fanglomerates is typically found near a lode source and it is not uncommon for the lode to be buried under a few feet of eluvium in a fanglomerate. This fact needs to be kept in mind by prospectors who search Arizona for nuggets in these fanglomerates – in other words, keep in mind where the gold ends up-hill as you could be sitting on top of a major lode gold deposit.

One of the few active stream placers in Arizona is known as the Lynx placers near the southern edge of Prescott 70 miles north-northwest of Phoenix in western Arizona where more than 108,000 ounces of gold were recovered as flakes and as nuggets up to 4 ounces. Another wet placer was discovered near the confluence of the Gila with the Colorado Rivers in southwestern Arizona, by has apparently been mostly mined out after more than a century of activity.

 

Arizona is known as the copper state even though it has produced more than 16 million ounces of gold since the 19th century. In addition to copper and gold; molybdenum, lead, zinc, silver, turquoise and other metals and gemstones have been mined. In the past few years, base and precious metals are mined at Morenci, Safford, Ray, Carlota, Miami, Monitor, Bagdad, Sierrita, Mission, Silver Bell, Pinto Valley, Mineral Park and Johnson Camp.

  

The majority of mines and prospects were developed on copper porphyry and massive sulfide deposits scattered along a distinct northwesterly trend within the Basin and Range province across the lower portion half of the state south of the Mogollon rim, which marks the southern edge of the Colorado Plateau and runs from Cochise to Mohave County. Many gold anomalies within the Basin and Range province and Transition zone between these two provinces suggest a presence of undiscovered gold and copper deposits.  

 

Figure 2. One of many open pit mines (Ray mine) developed in copper porphyry deposits in Arizona (photo by Sharon Hausel). The author leans on Monster Truck tire with mine in background.

 

Over the past several years, Arizona produced $6 to $8 billion in mineral resources annually, much of which is recovered from porphyry copper deposits where precious metals were recovered as by-products of copper mining.

 

 

Conclusion

Arizona has several mines and potential for discovery of additional gold and copper resources in essentially every district. Areas of notable interest for gold include Gleeson, Oro Blanco and Copper Creek in Eastern Arizona. Western Arizona has more known primary gold deposits. Some notable deposits in western Arizona include the Vulture mine and Rich Hill within the Wickenburg district, the Katherine and Oatman properties in the San Francisco district, prospects in the Wallapai district, gold in Lost Basin district, and gold in the La Paz district within the Dome Rock Mountains, Plomosa Mountains and La Posa plain between these two mountain ranges.

 

The Arizona Department of Mines and Mineral Resources reported $7.6 billion in minerals were recovered from mines in 2007 – much of this wealth was from copper and precious metals. Mining means a tax base and jobs for Arizona. It is highly likely that more jobs and a greater tax base could be created by stabilizing the border with Mexico, creating incentives for exploration companies and gold prospectors to explore, and most of all, applying significant tax cut and significant cuts to government bureaucracy. All too often in natural resources, permitting is duplicated at the county, state and federal levels. When I was the Vice President of US Exploration for a foreign diamond company, we had to obtain drilling permits from the county, state and US Forest Service just to drill one shallow 150-foot hole. Normally, it would have cost the company a few thousand dollars, but with permitting delays and government incompetency, it ended up costing us tens of thousands of dollars.

 

Arizona provides its own kind of challenges. Not only is the summer heat and lack of water a concern, but the danger of working in the field south of Phoenix must be weighed. Many mining companies will not explore near the Mexican border because of possibilities of running into heavily armed foreign drug runners with automatic weapons. In Wyoming, circumstances were different. One had to be more concerned with getting caught in a spring blizzard or worse yet, dealing with government bureaucrats waking from their stupor to over-regulate everything from rock collecting to walking on dirt.

Phoenix became one of the top kidnapping capitals of the world. Only Mexico had a higher kidnapping rate. I was shocked to find out that more American citizens were murdered by illegal immigrants in 2006 than soldiers were killed in Iraq and Afghanistan.

 

In a book on the Sierra Madre, Mexico, Grant (2008) reported the largest part of Mexico’s economy is based on selling and distribution of illegal drugs. The next major component is money sent by illegal immigrants living in the US to families south of the border – most of which is untaxed. This problem weighs heavily on Arizona’s budget. These dangers are a major concern for anyone wanting to explore in the desert for gold near the border.

  

References

Chenworth, A., 2010, The Bingham Canyon copper mine: ICMJ Prospecting and Mining Journal, v. 80, no. 2, p. 9-16.

Grant, R., 2008, God’s Middle Finger: into the Lawless Heart of the Sierra Madre: Free Press.

Hausel, W.D., 1982, General geologic setting & mineralization of the porphyry copper deposits, Absaroka volcanic plateau, Wyoming: Wyoming Geological Association 33rd Annual Field Conference Guidebook, p. 297-313.

Hausel, W.D., 1989, The Geology of Wyoming's Precious Metal Lode & Placer Deposits: Geological Survey of Wyoming Bulletin 68, 248 p.

Hausel, W.D., 1996, Economic Geology of the Rattlesnake Hills Supracrustal Belt, Natrona County, Wyoming: Geological Survey of Wyoming Report of Investigations 52, 28 p.

Hausel, W.D., 1997, The geology of Wyoming's copper, lead, zinc, molybdenum, and associated metal deposits in Wyoming: Geological Survey of Wyoming Bulletin 70, 224 p.

Hausel, W.D., 2005, Geologists Locate Giant Gemstones: Prospecting and Mining Journal, v. 74, no. 7, p. 7-9.

Hausel, W.D., 2005a, Geology of the Cedar Rim Opal Deposit, Granite Mountains, central Wyoming: WSGS Open File Report 05-1, 11p.

Hausel, W.D., and Hausel, E.J., 2011, Gold - Field Guide for Prospectors and Geologists, CreateSpace, 366 p.

Hausel, W.D., and Sutherland, W.M., 2000, Gemstones & Other Unique Minerals & Rocks of Wyoming - A Field Guide for Collectors: Wyoming Geological Survey Bulletin 71, 268 p.

Wilson, E.D., 1981, Gold Placers and Placering in Arizona: Arizona Bureau of Geology and Minerals Bulletin 168, 254 p.

Wilson, E.D., Cunningham, J.B., and Butler, G.M., 1967, Arizona Lode Gold Mines and gold Mining: Arizona Bureau of Geology and Minerals Bulletin 137, 124 p.