Total Pageviews

Tuesday, May 31, 2011

Gold Occurrences in Arizona

Superstition Mountain the reported home of the Lost Dutchman Mine.
Photo by Doug Dolde

As the home of the famous Lost Dutchman Mine on Superstition Mountain as well as several other lost gold mines it is apparent that there is gold in Arizona. The gold runs across Arizona in a line from Greenleee County on the New Mexico border to the Nevada border in Mohave County. The greatest concentration of gold can be found in Yavapai County in central Arizona. This concentration of gold ore extends to the southwest into La Paz County. There is a fine map by the Arizona Department of Mines and Mineral Resources that depicts the known resources of metals found in the state.

Placer gold in Arizona is a resource that was mainly tapped by the first prospectors that came into the state because finding this gold is so easy that it is often called “poor man's gold.” Although this may be true it also be remembered that every flash flood that occurs in Arizona brings more gold down from the mountains. Although placer gold is not as plentiful now as it was during the pioneering days of the 19th century it is still possible to find placer gold. There are probably many places in the state where rich gold deposits are still able to be found that were overlooked by the original prospectors.

One of the greatest difficulties faced by prospectors in Arizona that are searching for placer gold is the lack of water. Although it is true in many places you can prospect for gold using the dry wash method, but it still leaves you with the problem of having sufficient gold in your prospector’s camp to pay your expenses.

During the summer months it becomes extremely hot in southern Arizona, so hot in fact that I once observed that coyote was chasing a jackrabbit; they were both walking. This extreme heat makes for difficult prospecting that requires a considerable amount of physical labor. The best time to prospect under these conditions is during the colder months of the year.

Although a few prospectors are making out very well, and even more are making expenses, but the majority are not even making enough money to pay for their food. In these days of high unemployment if a man has enough money to afford to go prospecting rather than lying around there is always the chance that may find some high-grade gold deposits that have been overlooked by the early prospectors. It is this chance for sudden riches that drives gold prospectors.

Placer gold is a product of weathering where the gold weathers out of some gold bearing veins founded in hard rock. The gold is concentrated by the action of running water or wind in placer deposits. In some places in Arizona for placer gold as soon trapped in a cement like soil called caliche where it is virtually impossible to recover unless the caliche is broken up in a crusher just like hard rock.

Gold on Quartz
Photo by Rob Lavinsky

The state of Arizona contains more than 219 known metallic mineral deposits. A total of 26 of these districts have produced more than 100,000 ounces of gold, and 46 more have produced more than 10,000 ounces. This gold is found in many different types of mineral deposits that either produce gold is the primary metal or as a byproduct from mining other metals principally copper.

The most recent producer of gold the state was the Copperstone deposit that produced over 500,000 ounces of gold before closing in 1998. Parity posits that the state that are capable of producing over 100,000 ounces each but it just been waiting for the price of gold to go up. It is probable that these resources are being ramped up for production as you read this article. Among the gold deposits are those at: Yarnell, Newsboy, Moss, Mexican Hat, Tiger, Golden Eagle and Copperstone underground.  

Thursday, May 26, 2011

Gold Occurrences in Colorado

The Argo Gold Mine and Mill in Colorado
Photo by Dustin Moore

Whatever you may say about gold it sure attracts people's attention in a hurry so it was with the Colorado Gold Rush. The gold miners were egged on by the cries of, “Pike’s Peak or bust.” Rumors of gold date back to 1807 when the Mountain Man Zebulon Pike heard rumors of gold in the South Platte River. By 1859 rich deposits of gold were discovered in the mountains west of Denver when the miners abandoned the plains. The first placer mines were around Denver sparking the first Goldrush in 1858.  Gold was found in the following plains counties Adams, Arapahoe, Douglas, Denver, Elbert  and Jefferson. Small amount of placer gold is still produced from Sand & Gravel banks around Denver as a byproduct of gravel washing operations by the aggregate producers.

The district around Central City and Blackhawk was another important gold mining district that produced enough gold to bankroll the modern city of Denver with several hardrock mines being in the district.  At one time the author had dibs on part of the Bates - Hunter mine in Blackhawk. This is officially called the Central City – Idaho Springs District. 

The Teller House in Central City Colorado. Central City was the site of several goldmines during the 19th Century.
Photo by Hustvedt

Gold was originally discovered in this area on January 5, 1859, by a former California prospector named George A. Johnson during the Pike's Peak gold rush. He made his discovery at Chicago Creek where it empties into Clear Creek; this marked the first significant Gold strike that was made in Colorado. Jackson who originally came from Missouri was able to conceal his strike for several months until he paid for some supplies with gold dust then the word was out. What had attracted Jackson in the first place were the large number of hot springs that belched columns of steam into the air. Jackson's discovery eventually led to a gold rush.

 The presence of hot springs in the area is an indication that hydrothermal water sent shed themselves of their gold content into the surrounding rocks. The same hot springs gave the settlement a new name that was to be known as Idaho Springs. On May 5, 1859 another miner named John Gregory discovered a gold bearing vein but was later called the Gregory Lode between Black Hawk and Central City that was called Gregory Gulch. Within two months of this discovery several other gold bearing veins were also unearthed. These discoveries gave rise to the establishment of other mining towns in the area including Nevadaville and Russell Gulch.

This is Pike's Peak that gave rise to the cries of Pike's Peak or Bust during the Colorado Gold Rush

For a few years hardrock mining prevailed in the district until the miners exhausted the free milling gold that was prevalent in the shallower parts of the deposits. This Friday of gold or worked fine for the amalgamation process, but the miners could not recover any gold once they reached the sulfide ore at a deeper depth.

It wasn't until the invention of an effective smelter for the sulfide ore by Nathaniel P. Hill in 1868. This was an achievement that allowed hard rock mining to continue in the district where several other smelters were also built. It is estimated that by 1959 this district produced about 6,300,000 troy ounces of gold mainly from sulfide veins that were found in gneiss and granodiorite.

The early miners made their discoveries at the northeast end of the Colorado Mineral Belt, but it wasn't too long before they started heading southwest across the mountains from Idaho Springs the miners traced the Colorado mineral belt west along Clear Creek, then over the mountain passes to South Park and from there to head waters of the Blue River.

This was the Breckenridge district where the miners first discovered gold in the 1880s, By following the placer gold to its sources at the miners discovered that were veins in the hills containing gold. The miners even recovered some placer gold from the gravel benches to the north of the Blue River. Although gold production Peter now during the late 1800s, but was revived by gold dredging in 1908 along the Blue River. During its lifetime the Breckenridge district produced about 1 million troy ounces of gold. Today the gold mines around Breckenridge are all closed, but there are a few that remain open for tourists.

As early as 1859 prospectors had already found rich placer deposits on the west side of South Park in the valleys on the east side of the Mosquito Range in the principle districts of Fairplay and Alma.  These deposits were located at the headwaters of the South Platte River with others in the Tarryall District alongside Tarryall Creek. Later they found lode gold deposits in the mountains above Alma.  Some of these deposits were worked with floating dredges until 1952.  These gold miners left behind them the gravel ridges seen today. It has been estimated that production from these operations recovered about 67,000 troy ounces of gold. Altogether the Alma-Fairplay district produced about 1.55 million troy ounces of gold with over two=thirds coming from lode deposits.

The discovery of placer gold at Oro City in 1860 opened the pages on the colorful history of the Leadville District.  The placer deposits were exhausted within four years, but the discovery of lode gold in 1868 that later lead to the discovery of large silver deposits in 1877.  It was also in 1877 that the city of Leadville was founded.

The gold and silver deposits at Leadville were deposited in a paleo-karst environment where the rich ores were deposited in ancient river valleys that were later covered by volcanic deposits. The ore here acted as a replacement of limestone that is a common association for gold.  The ore was in the form of lead/silver sulfides with gold being produced as a byproduct.  It has been estimated that there were about 3.2 million troy ounces of gold produced from the Leadville District.

In 1870 gold was discovered by prospectors along the Wrightman Fork of the Alamosa River and a year later they found lode gold in veins where full scale production commenced in 1875 once they had build a mill.  In this district gold production continued until 1906, but became sporadic after that until all production ceased in 1990.  There were about 520,000 troy ounces produced in the life of this district.

At the southwest end of the Colorado gold belt gold is found in Telluride District where the gold is associated with several Tertiary volcanic calderas including the remains of the largest eruption ever discovered “La Garita.” Here the deposits are found associated with intrusives in the older sedimentary rocks as well as chimneys and veins in the volcanic rocks themselves. It is estimated that this district has produced about 6.8 million troy ounces of gold while it was productive. The same district also produced sizable amounts of silver, lead and copper during the same period.

The Cripple Creek district has produced the most gold in Colorado was not discovered until 1891.  After the discovery the towns of Cripple Creek and Victor were settled to take care of the needs of the mines as well as the miners. Altogether this district has produced more then 21 million troy ounces of gold. 

The Cripple Creek and Victor Gold Mining Co. was formed in 1979 with the idea of starting gold production in the district by working mine tailings from the old mines. In the period when they were active from 1979 to 1986 they produced around 150,000 troy ounces of gold.

In an exclusive interview with Jim Burnell of the Colorado Geological survey it was revealed that there are several hard rock deposits of gold that are ramping-up to resume production.  There has also been a considerable amount of activity from the small scale miners that don’t have to report their findings to the state.  According to Mr. Burnell there have been several exploration companies that have expressed an interest in Colorado gold, but for proprietary reasons they don’t want to have their names revealed.

To a limited extent gold mining is still going on in a large scale in Colorado, but the difficulties in permitting a large scale mine today make it extremely difficult to open a new mine. Several mining companies have tried opening some of the older mines that are grandfathered.

Tuesday, May 24, 2011

Gold Mining Practices under the Roman Empire

Roman gold was of this sort
Photo by Alaska Mining

Minerals brought great wealth to the Roman Empire as they were used most often as payments for imports. The Romans were using a sluicing whereby broken rock was washed through channels containing prickly shrubs, which caught the gold. This extraction technology was being taught all over Europe in mining schools, yet the majority of the individuals working the mines were slaves who were subjected to atrocious working conditions and incurred a high mortality rate.

In 22BC, Publius Carisius, in charge of the Ulterior Army, succeeded in securing several gold mining areas, while he advanced northwards through the Pajares and Manzanal passes. By the middle of the first century AD, Rome’s gold supplies were being maintained in Spain and Dalmatia.

At the end of the First Dacian War in Autumn 106, Dacia was incorporated as a province with a garrison of two or three legions, and stationed at Apulum. Dacian gold mining was exploited at Sarmizegethusa, a colony founded there, and workmen were brought in from Dalmatia. The process of Roman gold mining allowed for Romanization to occur.

Roman Gold Mining in Britain

The only evidence of Roman gold mining in Britain is at the Dolaucothi Gold Mines situated near Pumsaint, Carmarthenshire, Wales. Washing the gravels from the river Cothi was the most elementary method of gold extraction by the Romans. These unique gold mines are set amid wooded hillsides overlooking the beautiful Cothi Valley. 2,000 years ago, the powerful Romans left behind a glimpse of gold-mining methods. The harsh mining environment continued in the 19th and 20th centuries, ending in 1938.

Dolaucothi Gold Mine in Wales that has been mined since the days of the Romans
Photo by David Smith

Types of Romans Gold Mining

The Romans used several different methods for mining gold and extraction, the first being hydraulic mining. This process was also used by the Spaniards. Gold would be stored in large tanks or vessels and when the water was released into a water source or river, the sediments would wash away, leaving veins in the earth and particles of gold. Pliny the Elder gives an account of hydraulic Roman gold mining, made possible by his observations in Spain.

The Romans also utilized deep mining techniques which allowed surveyors to track the veins with shafts and tunnels underground. The remains of Roman dewatering machines were found during the 1880s and the 1920s when the Rio Tinto mines in Spain were being mined by opencast methods (a large tank contains smaller reservoirs below it. It is likely that this complex was used for washing powdered ore to collect the gold dust). Rio Tinto was one of the principal Roman gold mining settlements, having produced more than 2,000,000 tons of silver ore in antiquity.

The Romans also used trip hammers to crush the ore. However, after the Roman occupation, the Carreg Pumsaint was discovered; a block of stone erected many years ago after the Romans had left the site. These types of crushing stones have been found at other ancient Roman mines in Europe, and the hollows in the block were formed by a trip hammer probably worked by a water wheel or a "water lever"

With the decline of the Roman Empire, mining activity was halted until its revival once again in the 11th century. Mining made its emergence in Harz, in what is now eastern Germany, and by the 15th century, amalgamation and retorting processes were widely used in gold extraction.

Author Bio

Lauren Axelrod is a fulltime archaeology student and owner of the website Ancient Digger at:

Archaeology. Her articles have been featured on Treehugger, India Times,, and USAToday. Ancient Digger is also featured on the Discovery News Blogroll under Archaeology.

1. The chemistry of gold extraction. John Marsden, Iain House

2. Roman Spain. By S. J. Keay

3. The Roman Empire. By Colin Michael Wells

4. Money and Government in the Roman Empire. By Richard Duncan-Jones

5. National Trust: Dolaucothi Gold Mines. Quote

6. Gold Nugget Photo

7. Dolaucothi Gold Mines Photo

Sunday, May 22, 2011

Aqua Regia takes a Back Seat to a new Organic Process for Dissolving Gold and other Precious Metals

Solution of aqua regia in a laboratory
Photo by Thejohnier

Aqua Regia one of the few chemicals capable of dissolving gold and platinum group metals (PGMs) that was invented about 800 AD by the Arabic alchemist Gebar that was described in western literature in the 13 century by Paul of Taranto sometimes described as the “Pseudo Gebar.”  For centuries Aqua Regia reigned supreme until the development of organic solvents for gold were developed at the laboratory of Wei Lin and collogues at the Georgia Institute of Technology in the early 21st century. 

Aqua Regia is composed of one part of fuming nitric acid and three parts of hydrochloric acid that was used with a solution of tin chloride for the reaction forming the Purple of Cassius the only definitive test for gold until the invention of the Atomic Absorption Spectrometer in the 20th century.  Aqua Regia was also used in the gold refining process, but the same chemicals also dissolved PGMs making it difficult to remove PGMs from gold.  Lin’s new chemistry is capable of selectively removing the errant PGMs from gold by varying the constituents of the solution.

The new solution is based on the reaction of thionl chloride (SOCl2) and the organic solvent pyrazine.  Further experiments disclosed that by substituting other organic solvents such as N-N dimethylformamide (DMF), imidazole and pyrazine.  The gold can be recovered by calcining the resulting mixture.

Gold dust precipitated from aqua regia.
Photo by Greenhorn 1

A mixture of SOCl2 and DMS dissolves gold but doesn’t affect the PGMs making it possible to obtain 99.999 caret pure gold that is bullion grade.  By changing the recipe you can dissolve the PGMs without dissolving the gold.  This part of the process will make it easier to recover PGMs from catalytic converters then previous methods, and fuel cells in the future.

Even though the process can’t efficiently compete with conventional aqua regia at the present time Lin feels it will have uses beyond just dissolving gold and PGMs in the use of making nanostructures of the noble metals as well as recycling nano-coatings,  

Researches are ongoing with this technology, and it is expected that over the following years that advances in the technology will occur as well as new uses for the technology.  One of the major stumbling blocks that has to be overcome is the effects on the environment that is presented by this new technology.

Friday, May 20, 2011

Ferromanganese Nodules containing Gold

Ferromanganese nodules on the seafloor. USGS

Ferromanganese nodules are found more then a mile beneath the oceans where they are usually found in vast quantities on the abyssal plains. Most of these nodules are about the size of the potato although an occasional nodule may be found this the size of your kitchen table. At other times the modules have combined to make a pavement on the ocean floor. For the most part these nodules are composed of iron and manganese oxide, but they can also contain cobalt, copper, and other elements including gold and other precious metals. How these nodules form is actually poorly understood, but they are found in all the oceans of the world as well as its large lakes.

Because these modules are slow growing it takes about 1 million years to add a millimeter to their size, or about the thickness of the wire used in a small paperclip. When an ocean closes the nodules are swept down in the subduction zone to be recycled as new mineral deposits such as the deposits that are associated with all the earth’s suture zones. In the process of being recycled the various minerals are separated from each other forming different kinds of deposits including gold.

Ferromanganese nodules from the Pacific floor.
Photo by Marsin Zych

Altogether it is estimated that over millions of years these nodules have produced several billion tons of metal oxides. During the 1970s arose several nations that gave these nodules and a long hard look as a source of metals, but because they are submerged in the depth of 1 to 2 miles they quickly realized that the nodules were not an economic ore deposit.

The recent jump in commodity prices however has created a new interest in mining this resource. By using some technology borrowed from the undersea petroleum industry a company named “Nautilus Minerals Inc.” is the first company to explore the economic recovery of these resources; only their target is not modules is the deposits that are laid down by black smokers. There are other ventures that are now being undertaken in the Pacific Ocean that are also aimed to commercially mining these undersea resources.

It remains to be seen if any of these ventures are commercially viable, but time will tell!

How to use a gold pan

The usual size of the gold pan is about 14 inches that will hold about 20 pounds of gravel. Although you can take the gravel straight from the streambed it makes panning much easier if you use a classifier that removes all the stones larger than 3/8 of an inch from the gravel before you start panning. It is a good idea to examine these larger stones just to see if there are any gold nuggets present that might be thrown away with the oversized stone.

Gravel the largest piece in this picture in about 4 cm. This is typical of gold bearing gravel.
Photo by Stan Zurek

Gold is 19 times the density of water meaning that by shaking the gold pan combined with a circular motion when it is full of water will cause gold particles to settle through the gravel to the bottom of the pan. This is a process that you will want to repeat several times in the process of panning.

The gold pan is held at an angle so it's lower edge is submerged in water allowing the gravel to slowly pour over the rim and back into the stream. Periodically remove the pan from the stream and repeat the swirling motion to be sure you don't lose any of gold. Keep repeating this process until all that is left in your pan is an accumulation of black sand. It is in this black sand where gold accumulates. Always keep the edge of pan having the riffles submerged because the gold will be caught in the riffles rather than poring over the edge of the pan.

Gold panning showing how to hold a gold pan.  USDA

For the most part black sand is an accumulation of magnetite and hematite that our oxides of iron. Magnetite can be removed using a conventional magnet: hematite can be removed using a rare earth magnet. The magnetic separation of the iron oxides leaves behind a concentrate of the other heavy minerals that are found in stream gravel the most common of which are garnet and zircon as well as any other gold particles and other precious metals such as platinum. Gold and platinum often occur together!

Tuesday, May 17, 2011

Gold Occurrences in Utah

Mountains like this in Utah are where you can find gold.
Photo by Scott Catron

Most gold deposits found in Utah are in the mountains around Salt Lake City, and placer gold is found in the streams draining the Brigand district. Gold is also produced as a byproduct of the copper mining business at Bingham Canyon. Today most of the gold that has been mined in Utah was found during the Great Depression of the 1930s.  Please are gold is still found in the rivers and dry washes that are coming down the mountains in the area around Salt Lake City.

It has been recently discovered that there is gold present in skarn deposits in the Western part of the state that has a potential for gold. So far gold is been found in 146 of the skarn deposits in Utah that continues across the border into southwestern Montana. Skarn's are a variety of calc-silicate rock that occurs when limestone is intruded by igneous rocks. These rocks consist primarily of calcium bearing silicate such as diopside, wollastonite that are formed by the metamorphism impure limestone or dolomite. Typically the calc- silicate minerals have a greenish hue.

According to the Utah geological survey many of the skarn deposits are considered to be economic. Many of these skarn deposits also contain other or under rules such as sheelite one of the ores for tungsten. They also contain copper rowers such as chalcopyrite and the bornite.

Another source of gold in Utah is as a byproduct of the copper ores from Bingham Canyon, and Gold Hill. These copper deposits are found in porphyry that can also contain molybdenum and Gold.

Gold can sometimes be found as detrital gold in sedimentary rocks especially in the sedimentary rock conglomerate where it is found as fossilized placer deposits.  Conglomerate is nothing more complicated then a gravel deposit that has been turned to stone.  The largest gold producing area in the world, the Witwatersrand in South Africa is conglomerate.  This one area has in just over a century produced 40% of the gold that has ever been mined.  Gold is also produced from conglomerate in the Abitibi gold belt in Ontario and Quebec from conglomerate at Timmins Ontario.

Gold is often found associated with marble especially where it has come into contact with intrusive magma.  Often these deposits occurred during the Mesozoic era when dinosaurs roamed the Earth.

A crystal of bixbite on a matrix of rhyolite
Photo by Rob Lavinsky

Gold is not the only mineral those found in Utah that has great worth. The state gemstone of Utah is topaz that is found in topaz rich rhyolite as well as another mineral called “bixbite” that is reckoned to be more than 1000 times as valuable as gold.  According to the Utah geological survey bixbite is even more valuable than diamonds. If the stone was cut and polished it is worth far more than $2000 per carat.

Friday, May 13, 2011

Gold Mining Practices in Ancient Egypt.

The Ancient Egyptians were highly skilled in the mining of gold, made possible by the “alluvial spoil heaps and quarries which still bear witness to their activities”. Egyptian gold took two forms, dust or powder from alluvial workings and ring-shaped ingots cast from the smelted gold produced in the mines.

The Turin Papyrus Map is dated to 1100 BC is now at the Turin Museum. This map is rumored to be the oldest map in the world and it demonstrates the many gold bearing regions in the eastern desert of EgyptThe area shown is in the Wadi Hammamat between the towns of Quina and Qoseir. A network of roads intersects the mountainous regions and the inscriptions illustrate where gold was being mined in Egypt.

This is the right half of the above map.

In 60 B.C. Diodorus Siculus traveled in Egypt to inspect the gold mines of the Egyptians. His impressions and descriptions found in his Bibliotheca Historica drew largely upon the account given by Agatharchides of the working of gold. Agatharchides was a Greek philosopher and historian who wrote about the Red Sea in several books and the successors in Alexandria, where he worked at the court of PtolemyVI. Unfortunately, his work has been lost, yet Diodorus Siculus has keenly described laborers washing out gold from crushed quartz.

"At the extremity of Egypt and in the contiguous territory of both Arabia and Ethiopia
there lies a region which contains many large gold mines, where the gold is secured in great quantities with much suffering and at great expense. For the earth is naturally black and contains seams and veins of a marble which is unusually white and in brilliancy surpasses everything else which shines brightly by its nature, and here the overseers of the laborers in the mines recover the gold with the aid of a multitude of workers” [1].

Workers worked day and night and were confined to their particular work area in an event they tried to escape. The ground which was rich with gold was first burned and the remnants of the burn were crumbled by hand. The overseer or guard would point towards the ground or a rock. The workers with the greatest strength were assigned the quartz and they would pound it with massive force. No skills were necessary, just brute strength and agility. The workers would tunnel through the quartz, following the cleavage points and seams, never in a straight line.

Young men would wind their way through the hollowed tunnels and collect the rocks which would have been cast down piece by piece. They then transfer their load to the middle aged men who pound out the stones with iron pestles, making coarsely chopped pieces. Those pieces are then transferred to the women and older male workers whom cast them into mills and grind them into a fine powder.

The final stage includes pouring the powder on to a marble slap which has been worked into a board. The board is set at a gradual incline, so while a worker pours a continuous stream of waterover the board, the heaviest of the elements settles. Using a delicate sponging method, they pickup any small earthy particles, imperfect to be exact, and what’s left is gold dust. The gold dust is placed in earthen jars and mixed with “a lump of lead proportionate to the mass, lumps of salt and a little tin, and adding thereto, barley bran; thereupon they put on it a closefitting lid, and smearing it over carefully with mud they bake it in a kiln for five successive days and as many nights”. Once cooled, all that’s left in gold in pure form.

Notton noted that this working of the gold, as it is carried on at the farthermost borders of Egypt, is effected through all the extensive labors here described; for Nature herself, in my opinion, makes it clear that whereas the production of gold is laborious, the guarding of it is difficult, the zest for it is very great, and that its use is halfway between pleasure and pain [2].

1. Diodorus Siculus, Book III, Chapters 12 to 14; C. H. Oldfather translation, Loeb
Classical Library, 1935, 115-123
2. Notton,J. H. F.Ancient Egyptian Gold Refining: A REPRODUCTION OF EARLY
TECHNIQUES. Johnson Matthey & Co Limited, London.
3. Pictures are in the Public Domain

By Lauren Axelrod publisher of the Ancient Digger at: http:// 

Nancy Twinkie goes Shopping for Prospector’s Supplies

It finally came to pass that Nancy Twinkie became so hooked on gold prospecting she decided that she should own her own prospecting gear.  So on one Saturday morning when it was raining off we went to a rock shop that carried the kind of gear she wanted.  It was quite a drive to the rock shop since the nearest one to where we lived in Connecticut was about forty-five miles away on the other side of the Connecticut River in East Hampton.  Although Connecticut isn’t exactly rock hounding country there are enough to support a few rock shops; this one is the largest in the state. 

While I was talking to the owner Nancy was poking around in the store for what she wanted, and they had enough of fixings to satisfy her wants.  The first thing she bought was a gold panning kit that included two pans one was 14 inches in diameter and the other was 10 inches.  The kit also had a 14 inch classifier along with a pair of tweezers, a small magnifying glass, and a snuffer bottle for snuffing up small flakes of gold from a goldpan.  There were even a couple of plastic vials to hold the gold.

Then she bought a folding shovel like the kind you use in the army to dig a foxhole.  Although many people would call this a folding shovel I learned the hard way that it is also known in certain quarters as a “hip spoon.”

Nancy went whole hog that day, and bought some other gear for rock hounding.  This collection included a 22 ounce Estwing rock pick, a four pound Estwing cracking hammer, a 1 inch chisel about a foot long, and a bull point of the same length. 

After collecting this gear we stopped at one of those Big Box stores and bought a pair of work boots and a zipper overnight case to carry all this gear in.  The goldpans didn’t fit, so she also bought a backpack.  That finished her collection, so with that we spent the rest of the day rock hounding. 

This is the part of Connecticut where there are several large pegmatite mines many of which have some really rare minerals, so we went to the Strickland Quarry for collecting.  (At the time Strickland was open for collecting, but has since morphed into a golf course, and is closed to collectors.)

After parking the truck we noticed there was a large boulder composed mostly of cleavelandite just on the edge of the parking area.  From the looks of that boulder it probably weighed more then two tons.  By examining the boulder I could see the blades of cleavelandite sticking out in all directions.  Knowing this was one of the signs that there might be pockets inside the boulder we decided to see what was inside and went to work on the boulder with my 8 pound sledge.   

It didn’t take long to find out that the sledge hammer wasn’t going to work so I went back to the truck for a single jack stone drill and a striking hammer.  This was some mining equipment I had inherited from my great grandfather along with some ¾ inch feather wedges. 
A single jack drill it pretty easy to use, and you can drill a hole with one in a hurry by hitting its upper end with a four pound hammer. Each time you strike the drill you have to rotate the drilling steel a quarter turn so that every time the cutting edge of the drill is cutting into a new part of the stone.  We had to make four holes into the rock that were about six inches deep to hold the feather wedges.  It probably took agout 15 minutes to drill the holes and set the feather wedges.  After the wedges were set and tapped into place the boulder was split in half in less then a half hour from when we started drilling. 

Feather wedges can still be bought at mason supply stores, but old fashioned stone drills are no longer sold.  However you can make your own from a star drill by grinding off two of the flutes, or by grinding a radius on the cutting edge of a cold chisel.

Once we were inside the boulder there were many interesting specimens as the pegmatite was an LCT type.  In some of the cavities we found nice specimens of columbite,  but the best specimen was a nice crystal of blue beryl.  Most of the specimen was badly flawed, but there were some areas that were faceting grade that would probably have made gems weighing more then 10 carets.  That stone is still in Nancy’s private collection! 

Gold Deposits associated with Black Smokers

A black smoker and associated white smokers are found at spreading centers in the middle of the ocean.  What the smoke that is produced from one of them is in reality finely divided metal sulfides that are leached from the oceanic crust by seawater percolating through the ocean bottom to a depth of several hundred feet that is heated to a temperature that can exceed 300o C. As the mineral charged hot water is discharged to the open ocean it is suddenly cooled causing the dissolved minerals to precipitate out and form deposits of metals on the ocean floor.

A black smoker at the sea bottom.  The black smoke is caused from finely divided  metal sulfides.

Black smokers are located on a tectonic spreading center where two plates are being forced apart by upwelling of basaltic magma. If the black smoker were on dry land it would be considered a hot spring, but because they are at the bottom of an oceanic trench in waters that exceed 12,000 feet they have earned the name Black Smokers because of the plumes of metal sulfides that emanate from them. There are some of these features that have white plumes of metal carbonates associated with them, and they are known as white smokers.

A white smoker producing carbon dioxide gas and metal carbonates.

Most of the metals that come from these hot springs are copper, lead and zinc, but there are also other metals such as gold and silver that are deposited on the seafloor, or are carried away in solution from the site of the black smoker. Aside from the primary metals that are deposited as sulfides at the site there are a number of other secondary metals that are also deposited such as indium, germanium and cadmium.  These models are also produced as byproducts and during the smelting process.

These products are known as Volcanogenic Massive Sulfides (VMS) and are represented in several large deposits in Archean aged rocks. Two notable examples these are found in the Abitibi region of Canada as the Kidd Creek mine to the east of Timmins Ontario, and the Horne mine near Rouyn-Noranda, Quebec. These are VMS deposits that are on 2.6 billion years old that were deposited when the overall temperature of the earth was much higher than it is now.

The open pit portion of the Kidd Mine in Timmins, Ontario.  It is thought by many that the Kidd Mine is an ancient  black smoker.

Although gold is founded on the VMS deposits as a byproduct more often it is mobilized during the process of subduction where it is deposited in separate quartz veins, or other gold traps that are removed from the main VMS deposits. Examples of this can be found in the green belt deposits throughout the world. Even though the mountains are now worn down to their roots in many places these deposits originated as black smokers in the depths of the sea prevail on dry land.

The deposits of black smokers have dotted the surface of the ocean bottom on both sides of the spreading center. As these deposits are moving away from the spreading center they become covered sometimes to great depths with sediments raining down from the surface of the ocean until they eventually are subducted beneath a continental or other oceanic plate where they are recycled to form other types of mineral deposits.

Geologists like to talk about the many different cycles that affect the Earth one of these might just as well be the mineral cycle that occurs as the Earth recycles the different mineral deposits forming new and different deposits of the same mineral.

Tuesday, May 10, 2011

Gold Occurrences in Nevada

The Goldstrike Mine in the Carlin Trend of Nevada   USGS

Placer gold has been found in 14 of the 17 counties in Nevada in the form of either commercially viable deposits, or deposits that are potentially viable. Most of these deposits are located in the northern and western part of the state. Many of these deposits were worked out by early prospectors, but there are many areas in the state were overlooked that can still afford a working wage if they are developed. It is especially important to hunt out areas where virgin gold can be found that were never mined in the past.

Much of Nevada is so arid that the early prospectors had several different methods of dry washing their gold bearing gravel. One of the biggest problems they had in processing placer gold was the presence of lots of caliche, a type of hardened sub-soil that attains the hardness of concrete. 

It is felt by many that the discovery of gold is an ongoing process with much of the gold still waiting to be discovered.  By drilling in the basin and range province of the United States exploration geologists are finding even richer deposits of gold then there are in the Carlin Trend.  It is claimed that prospecting in the state is exciting because there is so much undiscovered mineral wealth present, and it isn't all gold.

Placer Gold
Photo by Nienetwiler

Nevada is also the home of unique deposits of finely disseminated gold that was discovered in the 1960s by Newmont Mining Company who developed a method for extracting the gold. For the most part these cool deposits are found in an argillaceous limestone that has been subject to enter thermal alteration. This is the famous Carlin trend of cool deposits where the gold is so fine it can only be seen with electron microscope, and at times goals of the limestone was represented by a single ion.

Gold of this sort is mined using the heap leaching method of recovering the gold values. He teaching consists of piling up a heap of crushed stone about a quarter inch in diameter and treating it with a weak solution of an alkali salt of cyanide. The heap is piled up on a watertight floor that slightly slopes towards the center and all the pregnant liquor from the gold leaching process is directed to a sump where it is collected for treatment to recover the gold.

Although there are several different techniques used on the ore one of the most common is treating the pregnant liquor with powdered zinc. The gold in the liquor chemically replaces the sink it is collected as a black powder that is further refined into pure gold.

Nevada also produces many gemstones including precious opal and turquoise. The precious opal comes mainly from the Virgin Valley, and the author used to buy some really beautiful turquoise from the area around Crescent Valley.

Sunday, May 8, 2011

Gold Occurrences in California

There are 13,470 gold mines or prospects according to the California Geological Survey that are located in the state. These gold mines are found in all parts of the state but the greatest concentrations are found northeast of Sacramento in the foothills of the Sierra Nevadas. Another large concentration is found in the northwestern part of the state in the Trinity and Siskiyou Counties.  An even smaller, but dense concentration is found in Calaveras, Tuolumne and Mariposa Counties.  Gold has been found in most of the counties in the state but there are a few counties mainly in the Central Valley where gold was never been reported.

Mine buildings at the Bodie California gold mine.
Photo by Thomas Kriese
Although there were scattered reports of gold being found in California before 1848 it was the accidental discovery of gold at Sutter's Mill in Colema by John Marshall.  Marshall’s discovery touched off one of the greatest mass migrations in the history of mankind. It has been estimated that more than 200,000 people migrated to California between 1848 and 1852. California was admitted to the union in 1850 as the 31st state under the Compromise of 1850.

Crystallized gold from California.
Photo by Rob Lavinsky

The first mining that occurred in the beginning of the 1849 gold rush was from placer mines that were often operated by individual miners. With the discovery of the mother lode mining quickly moved underground, but it was no longer in the domain of the individual miners rather it was pooling of money required to operate lode gold mines. This new type of mining ushered in the day of large gold mining companies that made it virtually impossible for the individual miner to stay in the gold mining business. The industrialization of the gold mining business left plenty of opportunities for the individual to work as a miner in the large mines.

Although most of the placer gold was mined during the mid-19th century every spring freshet brings out a new batch of gold from the surrounding hills and mountains where it is concentrated in the rivers and streams. Although most of the gold mining in California today isn't hard rock mines a substantial portion of placer gold is still produced in the state. Much of this placer gold is produced by small-scale miners rather than the major corporations.

Hydraulicking a type of placer mining in California where high pressure water was directed against gold bearing gravel deposits.  This particular operation was at Dutch Flats, California.  Hydraulic gold mining was outlawed during the 19th century as one of the first environmental laws ever passed. 

Even though the areas that were extensively mined during the gold rush are still capable of yielding placer gold in quantities large enough to attract the small-scale miner, gold can be found in virtually all the rivers and streams in the state, as well as along the beaches of the Pacific Ocean.

Saturday, May 7, 2011

The Tools of the Trade by Raymond Kukkee, Prospector

Prospecting country in Northern Ontario this is a photo of Kakabeka Falls called the Niagara of Canada.  Ray lives in the town of  Kakabeka Falls, Ontario.
Photo by Hans Jurgen-Hubner

Raymond Kukkee has been a hard-rock prospector in Northern Ontario for over thirty years, and the following article is built on his experiences while prospecting. 

What you should take with you on a prospecting outing is always a good question. It's always better to have something and NOT need it, than to be 60 miles out on the trail wishing you did bring it along.
 Here's a list of what I usually take along on my day trips.  Remember I 'm going out in my truck and might be  dragging  a 4WD Quad along to save the feet too!

Even for a 2 hour walking trip, I take most of  the following tools and other helpful items,  but once out in the field  at times,  I may leave some  items  in the truck, depending on the outing:

•    A jeweler's loupe,  I use a 25x triplet
•    Topographic  and geology maps of area to be explored
•    Prospector's license*
•    Pad and pencils. Take extra pencils, they get lost easily. A compact  waterproof paper notebook is handy
•    A compass  (liquid-filled, good quality)  I use a Silva  or Brunton surveying type  c/w signaling mirror
•    A GPS unit capable of mapping,  projecting and tracking way points.    My present GPS is a Garmin GPSmap76CX, which is reliable and runs for a couple of days on 2 AA batteries.
•    Safety glasses for bashing rocks.  We only have ONE set of eyes so take care of them!
•     A compact first aid kit
•    A belt-carried hunting knife -6"   and / or a multi-tool type belt knife
•    A prospecting "pick" hammer. (In this area we have a special tool called a "Tweedie" tool named after Ron Tweedie, the inventor and maker.  It is a 36" short-handled   hammer with a 3" flat blade opposite that can be used both  for whacking rocks and grubbing, to remove moss/dirt for stripping.  (In prospecting that is convenient, it saves you bringing along a wide pick.)   At times it might be the only hammer you carry.
•    A sharp cold chisel  ½" x 12" long
•    A 4-lb short- steel- handled  "crack hammer"  unbreakable (Estwing) for serious sample removal.
•    Some paper to wrap special delicate specimens
•    Plastic sample bags 6-10  mil  8x14"  are good,  but  you can use recycled plastic bags of any type. I take along heavy recycled 1-liter plastic milk bags when available.*
•    A red or orange wax pencil for marking stakes or posts.
•    Fluorescent flagging tape to mark sample locations
•    A black marker to write ON the flagging tape
•    A short-handled ox-head axe--for cutting claim posts.   If cutting claim lines, I also  take along a
•    Swedish brush axe which is the bow design.
•    A folding shovel for the back pack, and a long-handled shovel for the truck.
•    A very compact emergency 3"x4"x 2"fishing outfit, a few hooks, line, sinkers, and a small lure.   Maybe a small collapsible fishing rod!
•    Wide-brimmed floppy hat that will cover the ears.
•    Full face mosquito net that fits over the floppy hat for extreme insect conditions.
•    Fly dope.   Various types, it must work on blackflies, mosquitoes, and deer flies.  But is generally USELESS for those tiny noseeum sandflies in hot weather
•    Extra socks to keep the feet dry.
•    Heavy boots that have high ankle protection. Waterproof boots are best
•    Rain gear--lightweight rubber but full body coverage including a hood--or the  Gortex type
•    Long-legged pants,  NOT shorts.
•    Long-sleeved shirt and jacket
•    Leather gloves, or good quality cotton gloves with leather facing
•    Eye-glasses.  I always take a spare pair!
•    Sunglasses
•    Sunscreen: 40SPF minimum.
•    A compact, folding dome tent.
•    In some areas, a snake bite kit is a good idea.
•    For SOME locations, belt-carried  Bear pepper spray is important.
•    Aspirin or Tylenol.
•    Medications if you need them.
•    Drinking WATER:  NEVER  allow yourself to become dehydrated.
•    Matches. Use safety matches, protected to keep dry, or bring along a Fire Starter (magnesium) bar.
•    Food:
•    Dry Trail mix for snacks.  
Oranges are good too, and keep well
•    Lunch!    The best part of prospecting out in the bush!  I almost always take cheese sandwiches going on day trips into remote areas.    Take food that will still be good for a week even if it's squashed, melted, or beaten up. Dehydrated type foods are good for long trips too.
•    **  NOTE:   NEVER take meat sandwiches or chicken with mayonnaise out into hot weather, they can be unsafe to eat after a few hours in summer heat!
•    Hot Coffee or Tea in a thermos for cold days.
•    A small single-burner propane stove can be handy!
I guess that’s about all you  can carry, but then there’s a spare key for the vehicle,  spare gasoline, a couple of quarts of oil, some tools, a Jack-all, a couple of spare tires, and walkie-talkies if you have them.

Don’t forget that 8-lb sledgehammer for serious work, a compact bow saw for firewood -- and your driver’s license.

I guess that’s about all you should need at this point.   I hope you’re having FUN!  If I think of anything else, I’ll let you know!     Stay safe!


* Needed in Canada!

Big Boys Toys for the Gold Patch

A sampling of some of the equipment that is produced by Goldlands at their plant in Bellingham Washington

As far as we know there is no formal definition for the Gold patch, so we will make one up right now. Our definition of the “Gold Patch” is that it is a large commercially viable deposit of placer gold from which the gold is recovered using specialized large-scale equipment.

Making a large-scale deposit of placer gold payoff is strictly a function of how much gold bearing gravel you can process in a day. You're not going to do it with neither a gold pan nor any other equipment that is used by the small-scale miner this takes some pretty good sized toys. One such company that makes this kind of gold recovery is Goldlands from Bellingham, Washington. The company makes a line of gold mining equipment specifically for the recovery of gold, platinum group metals and gemstones.

Goldlands manufactures a complete line of heavy industrial equipment suited for large scale operations for the recovery of gold and other heavy minerals.  They have some of the most innovative equipment in the field as they have been doing so since 1977.  Some of this equipment includes as quoted from their Webpage:;

“1.   The Gold SONIC CONCENTRATOR or "Live Sluice", a two tray, heavy duty high oscillation gravity concentrator for hardrock and alluvial precious metals extraction and concentration.  These process from 50 to 150 Tons per hour and can be placed in series for higher capacity operations.

Goldlands live sluice concentrator

2.   Portable 
HELICOID CONCENTRATORS called the Goldland "Blasters" which continuous feed and upgrade the metals and material.  These units include the MicroBlasters, GoldBlasters and NuggetBlasters, starting at the smallest test units of 1 Ton/Hour, up to high capacity of 150 Ton/hr units.

TROMMEL/SCRUBBERS:  These clay scrubbing units are portable a trailer mounted and process from 50 to 150 Tons/hour.  The gravels are washed thoroughly, releasing any gold baring material from gravel conglomerates.
Goldlands trommel unit

4.    Rotary 
MICRON GOLD CENTRIFUGES:   These centrifugal cylinders have a series of baffles within.  The units are rotated at a high but regulated speed which breaks the water tension and forces the micron, floating gold and precious metals to be captured and build up in the interior baffling.  The units are then purged at the end of shift and the concentrate extracted.

SCREENING SYSTEMS:  These high vibrating units have 4-6 decks and can be adapted to process either concentrate or bank run material. They are ideal for micron gold recovery.

MINING PROPERTIES AVAILABLE - Goldlands operates its own gold mines and has properties available for new customers who wish to learn to operate Goldland's mining equipment.   Learn and earn at the same time!”

Goldlands ships their equipment all over the world dismantled in shipboard containers.  There have even been reports of some of their equipment being used in Africa producing as much as $25,000 worth of gold per day.