Not long ago I was asked an interesting question by a fellow prospector. He wanted to know why after two years of hunting he had only been able to find an assortment of smooth polished nuggets, but no quartz-gold specimens. The only answer I could offer was that perhaps he was not looking in the right places.    

        Detectorists interested in searching for hardrock (or specimen) gold should focus their efforts on the “old-timers” shallow exploratory diggin’s, mine dumps, the hillsides surrounding the workings and haulage roads. Where? Arizona, California, Colorado, Idaho, Montana, New Mexico, Nevada, Oregon, South Dakota, Utah, Washington and Wyoming (Straight, p. 12).

        The rock material removed from a mine was typically sorted into various piles according to its perceived value. The worthless waste rock (or gangue) was tossed out, while the ore was classified into low and high grade piles. Obviously the early miners were unable to assay the gold content of each and every rock, so much of the evaluation was done by hand. These hand sorters were highly skilled and had a keen eye for spotting high-grade samples, however no one is infallible and eventually they were bound to miss a few. Hardrock gold can be completely hidden within quartz, or some other mass, and not visible to the eye. As a result many rich pieces of ore were able to slip by unnoticed and cast aside with the waste rock.

        Other times a mine may have been shut down before all the stock piled ore could be crushed and was left piled up near the mine. This is especially true of the gold mines operating prior to 1942, which were forced to shut down after the onset of the Second World War.

Mine Dumps

        Remember, mines have dumps - mills have tailings. It would be a rather disheartening experience to detect mill tailings in hopes of finding a specimen or nugget, as all the ore has been pulverized into a fine powder. The dump material, on the other hand, has not been completely crushed. It is here that electronic prospectors will have the best odds of locating detectable hardrock gold.   

        While dumps may contain gold-bearing specimens, they are notoriously trashy areas. I have found square nails, wire, tacks, staples, tin cans, pipes and scrap iron scattered around virtually every mine I have ever visited. Most people; myself included, can tolerate a certain level of trash for only so long, and after 3-4 hours of digging nothing but rubbish it is very difficult to remain motivated. However, I have come to realize that this old discarded rubbish is actually a blessing in disguise.

        Within the last year I have been lucky enough to find several ounces of hardrock gold from a dump outside of Congress, Arizona. In 1998 there was a rich nugget patch discovered near the mine, but after a few weeks of detecting by myself and a handful of others, it was quickly exhausted. Then a couple of months later I decided to give the area another try. The patch had been worked out, but as far as I knew the heavily trashed dump had never been touched. By the end of the day I had dug 78 pieces of trash, as well as 3 ounces of specimen gold. The gold had been there all along, but none of us had taken the time to wade through the trash. Since then my father and I have removed most of the surface litter and have picked up several additional ounces. I would imagine there is at least twice that much still buried under several tons of waste rock!

        My friend was detecting a very popular area and received a loud signal from a piece of quartz mixed in amongst a mine dump. He said there was no obvious sign of gold, but he decided to pitch it into his backpack anyway. Later that night he cracked it open and there in the center of this quartz rock lay a beautiful half ounce lump of gold! I often wonder how many other detectorists heard this signal, but left the rock thinking it was just another piece of iron?

        Most detectorists that encounter a heavily trashed dump will dig a few targets and then move on. This is good news for the rest of us, because if there are any specimens in the dump, there’s a high probability they are still there. This is exactly what happened at the dump near Congress. All you need to be successful is a little more patience than the last detectorists.

        Caution must always be used while hunting around hardrock workings. Many of the old mines have been left wide open and can be extremely dangerous. One unfortunate slip and you could find yourself in quite a predicament. I suggest staying away from the old shafts, pits, etc. and instead concentrate on the nearby dumps.

        Trying to tackle the whole dump at once is too difficult a task. To make the job easier, split the dump into imaginary sections and only hunt one area at a time. By limiting your search area you will have a tendency to be more thorough and less likely to miss targets. Keep the coil as low as possible, pack out the trash you detect, and always investigate any rocks (especially quartz) which produce a clearly audible signal. If you begin turning up some nice pieces it may be worthwhile to do some digging using a sturdy rake and hoe. This will allow your detector to gain additional depth and recover targets that otherwise would have been missed. 

        Sometimes dumps are so badly trashed that it is virtually impossible to swing the coil. This situation doesn’t arise very often, but when it does you might consider using a different technique. This process is slow, but it is simple to do and it does work. First, you must be confident that the mine in question was actually a gold mine (preferably one that had free-milling ore). By free-milling, I am referring to gold particles not chemically combined with other elements within the ore. Next, scour the surface of the dump and pick up any interesting samples exhibiting red, orange, yellow, green or black staining and toss them into a five gallon bucket. Then, take the bucket(s) over to your detector, position it in an area free of any metallic objects (I usually set mine atop a plastic milk crate), then repeatedly pass each sample across the stationary coil. If no signal is produced, cast the sample aside. If a sample produces a signal (an indication of possible gold content), it should be placed in a separate bucket.

        Iron-bearing rocks produce a varying degree of responses on a metal detector, depending on the design of the machine. Most of the time these false signals are just the iron mineralization, and not necessarily gold. However, gold and iron are closely associated and almost always found together. Specimens as well as nuggets, can be disguised by a coating of some other mineral, such as iron or maganese, and not resemble gold at all. Just to be safe, I recommend saving all samples which produce a decent signal.

        After you have accumulated a collection of these potentially gold-bearing rocks you must examine them. This should be done outdoors in direct sunlight. With the help of a quality loop or magnifying glass, slowly scan the rock looking for any sign of the yellow metal. Sulfides such as pyrite (fool’s gold) and chalcopyrite are often mistaken for gold. Here are two quick field tests you can use to help determine if your sample is actually gold. First, shade the sample with your hand. Sulfides will lose their luster in the shade, whereas gold will always appear brilliant. Second, turn the sample at various angles while watching the suspected area. True gold will always shine regardless of which way it is turned, whereas the sulfides have a tendency to shine at one angle, but not another.

        If gold is not apparent on the surface of the sample it should be cracked open with a rock hammer and reexamined. If you still do not see a speck of gold, the sample should be crushed (dollied) with a hand stamp or mortar and pestle, and panned at a later time. However, if the rock has visible gold you may want to refrain from crushing it, as it could be worth more as a specimen.

        Unfortunately this process can be time consuming and will only work for those samples containing a large concentration of gold. Those containing small disseminated particles may not have enough metallic surface area to be detected. However, if you hate digging a heap of rubbish this technique may be a welcomed alternative to standard detecting.

        Keep in mind that if none of your initial samples prove to contain the yellow metal, it doesn’t necessarily mean there is no gold to be found on the dump. It probably just means that not enough material was tested or the right samples were not collected. Numerous tests should be conducted before deciding whether to move on, or continue hunting the area.       

Hillsides

        Most of the minor, free-milling hardrock gold veins worked in the western United States were epithermal in nature. Epithermal veins are by definition: a shallow hydrothermal ore deposit formed about a half mile from the surface by solutions related to a volcanic rock source.

        In the past, epithermal deposits often frustrated many old-time prospectors and miners due to their tendency to rapidly “bottom out.” Now, under a few inches of soil on a sparsely sagebrush- covered slope within a hardrock mining district, a persistent detectorist can still (with a little luck) discover an overlooked vein. Then with only a detector and a few quality digging tools, he/she can quickly and efficiently recover a possible gold pocket that was missed by the old-timers (Straight, p. 10).

        I would imagine that there are many yet-undiscovered, small epithermal gold-bearing veins scattered on the hillsides surrounding these old workings. Always carefully detect the hillside below the exposure of these outcropping for overlooked shallow quartz-gold pockets, specimens and patches. Most of the really large specimen-type nuggets you may have read about, are obtained from superficial deposits and have been found at or just below the outcroppings of rich veins (Lindgren, p. 226).

        Pockets are hard to find, but rest assured, they are still out there. In the summer of 1999, I helped my father chip out a pocket containing 2.5 ounces of crystalline gold above an abandoned gold mine in the Northern Territory, Australia. Another friend of mine detected a tiny pocket near Prescott, Arizona with his Minelab XT 18000, and recovered approximately an ounce of foil-like gold.

        While detecting the hillsides keep an eye out for traces of free quartz float (especially those pieces showing iron staining). The “float” themselves may contain gold, but better yet, they could eventually lead you to a gold-studded outcropping, a pocket or a residual patch.

Haulage Roads 

         The term haulage road refers to the route the ore was taken from the minesite to the mill. The wagons or trucks used to transport the ore were often loaded above normal capacity in order to save money and maximize output. As you may already know, these dirt tracks were often full of tight bends, switchbacks, curves and bumps. With this in mind, it would be reasonable to assume that some of their precious cargo may have spilled over the top and may still be lying beside the road. Sometimes the wagons or trucks would break down on their way to the mill and the ore would have to be dumped. Often the trucks were repaired and the dumped ore was forgotten. About three years ago a few gentlemen located a pile of dumped ore somewhere near Sun City, Arizona and recovered quite a bit of gold. Some of the quartz was coated with a form of sponge gold, and because of its unusual appearance it sold for a hefty price.

        Other times the ore was intentionally stolen by the drivers on the way to the mill. At some point the wagon was stopped and maybe a quarter or more of the ore was removed and hidden somewhere in the bushes, only to be retrieved that night by the thieves. Shady activities such as this were commonplace at the historic Vulture Mine, located outside of Wickenburg, Arizona. Who knows how much gold ore is still hidden along the old haulage roads between the Vulture and the Hassayampa River!

        If you plan on hunting haulage roads look for abrupt changes in the track such as switchbacks and tight bends. Then detect along the side of the road for any pieces of lost ore. And if you ever come across a pile of rock that seems out of place, it may be worth the time and effort to quickly run your detector over it. You never know, it might just turn out to be a rich pile of stolen gold ore!

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