Saturday, November 19 2022
If you’re used to water mining, having success in the desert might seem challenging— that is until you start thinking of desert ground as a massive sluice box. Many of the principles you’re used to when prospecting and mining in waterways, will translate into desert mining. The most important thing to remember is that water is crucial to gold movement. Unlike a running river or creek with highs and lows, desert placers are much different in that gold is moved quickly during a flash flood, leaving gold stranded as opposed to being moved further by continual water flow in a creek. During a river high-water event in a non-arid area, gold is moved over a larger area by massive water flows that continue until the water slows as the source dissipates its energy. Spring snow runoff is a good example. Rivers rise and sometimes flood based on the upstream water source. When the snow has melted, the river will slowly get back to normal. In the desert, gold is moved in the exact same way with the exception that water powerful enough to move gold does so and then just simply stops. In a flash flood, gold is moved very violently and often a very short distance, sometimes percolating into valuable pockets. Here’s where the difference between water and desert mining principles comes into play generally flood gold will concentrate in areas that do not meet the standard thought of inside bends and where the water flow becomes lower. For the most part, desert mining experts recommend staying out of the washes, gulches and dry river beds— that is unless you clearly see exposed bedrock. Gold will settle fairly quickly when it is trapped behind jagged bedrock and small fault lifts that have not been worn down over time by constant water flow. It IS true you can find areas of concentrated gold-bearing material in the washes, however, the amount of time and energy to get through feet of overburden is usually just not worth it, especially when there are higher values to be found outside of the wash. Follow the leads out of the wash to where the gold lives in higher concentration. Test and sample areas you see with a great deal of runoff from a tributary coming into the main wash. Here you are only digging through the current flood layer and testing for flood gold. Make your way out of the wash carefully looking at the bottom of the tributary and the areas where the water flowed into the tributary. Look closely for jagged bedrock and slight lifts in the ground and then prospect. Continue to test each of those spots. What started as a few specks of flood gold in the main wash can lead to larger and larger deposits on the flats or in slight inclines across the desert floor. Keep in mind that when a flash flood is dissipating, there is not enough energy to move a lot of rock, but the sand will continue to flow a bit, creating great clues. In general, cool season precipitation (October through April) is the most extensive source of rain in the desert regions. Rainfall is more widespread and of relatively long duration during the cool season. On the other hand, warm season precipitation (May through September) results largely from short monsoon-type thunderstorms. If you’re ready to head to a sunnier climate this winter, keep these tips in mind and you just might find enough similarities between water and desert mining to make you return every year. Good luck! Friday, September 30 2022
In an area either rumored or known to hold gold, where should you look first? The creek, the surrounding hills, washouts, or just where? The characteristics of the gold in that area will help you to know where to start. If the gold is flat and pounded, that indicates it’s been in the water a long time. If the gold is coarse and chunky, you know you’re getting closer to the source. When gold is smoother, stop and go back to the coarsest gold and start working upwards until you find the source.
Keep in mind that gold is gold, so there isn’t necessarily a better type of gold. Some is just easier to recover. There are only two types of gold deposits. The first type is “lode” which is simply everything that is still in the matrix and in the ground, and the other is “placer” —or everything else. Lode deposits refer to gold that is still locked within its original solid rock formation. This formation of gold generally starts as a vein in rock and is formed over millions of years. Since the gold is locked up in rock, and can be mixed with quartz, calcite, pyrite, and other minerals, lode gold usually requires specialized mining techniques to extract. Lode mining takes a lot more equipment and generally a lot more expense and is usually undertaken by large commercial operations instead of the average prospector. Placer gold is the gold that most prospectors are more familiar with. Placer gold isn’t really any different than lode gold. It is simply a concentration of that same gold that has eroded and traveled away from the vein. Since gold is very dense, it will move downhill much slower than the surrounding sediment. It tends to become concentrated on or near the surface of the lode, forming a “residual placer” close to the original bedrock exposure. Gold found downhill from the immediate outcrop above the nearest watercourse is called an “eluvial placer.” Once it reaches the nearest waterway and is transported by flowing water, the gold now is known as “alluvial placer.” The origin of the dust, flakes and nuggets found by panning and sluicing is usually from a vein up on a nearby mountain. Bench placers were originally stream placers. Benches are simply where the water used to be, maybe even millions of years ago. They are formed by erosion or geological events such as uplifts, earthquakes or plate drops that changed the stream flow. Some of the most profitable mining is performed on benches. Many benches are highly concentrated by the alluvial deposits that still feed them. Stream deposits are the last resting place for gold. Once the gold has been released from the lode, gravity and nature does the rest. And unless gold gets stranded on a bench, it will find its way to the water someday. It may take a million years, but it will get there. When deciding where to begin prospecting, most of the time you’ll want to start panning in a water way, or a wash in the desert where water once flowed. Then let the gold tell you where to go from there. When the gold gets coarse and ragged, start to move up, looking in reverse of how it got to the spot where you found it. In addition to panning and sluicing you may wish to upgrade your mining efforts with a highbanker or power sluice, dredge or trommel. Moving soft soil or river gravel is obviously much easier than breaking rock, but for small scale miners, a rock crusher can pulverize 2 or 3 inch sized rocks into powder in no time. Move more material faster— get more gold! Saturday, November 27 2021
If you’re ready to head to a sunnier climate this winter to do some desert prospecting, understanding the weather and topography can add to your success. Before loading up and heading to the Southwest, only to be disappointed by bad weather, first check out the weather patterns for the last 60 days and the predicted weather for the next 30-60 days. Why is that important? Well, it mostly comes down to rainfall— how much and how fast. For example, if there will be a lot of rainfall over an extended time, soils will be loosened and gravity will do its job and cause deeper, and sometimes more concentrated, pay streaks. In general, cool season precipitation (October through April) is the most extensive source of rain in the desert regions. Rainfall is more widespread and of relatively long duration during the cool season. On the other hand, warm season precipitation (May through September) results largely from convective precipitation in the form of short monsoon-type thunderstorms. Friday, April 27 2018
A good rule of thumb that most prospectors agree on is to look for placer gold on bedrock and within crevices in the bedrock. This simple principle makes sense— placer gold is heavy and dense and therefore settles at the lowest point as it is pushed around by flowing water. However, gold isn’t always going to make it all the way down to true solid bedrock at the bottom of all gravels. Instead, in certain conditions, it will be found ABOVE bedrock. When these conditions exist, gold will collect on “false bedrock.” For example, a clay layer in streams can act like bedrock and yield more gold than the true bedrock below it. Another situation where gold cannot make it to bedrock is where the streams and gullies have “caliche.” Caliche is a form of cemented gravel often found in desert areas. The gravel is deposited by water flows, just as it would be in any other stream. The difference is that the water contains dissolved calcium salts, and as the water dries up in the streambed, the calcium salts turn into calcium carbonate or calcite. This material gets deposited on the gravel a little at a time and eventually the calcite glues it all together into a solid mass. The solid mass then acts like false bedrock and any new gold flowing across it is stopped in its downward movement by the caliche. Friday, December 29 2017
Given a choice, most miners prefer using water to wash and run material, but in some dry, remote areas that is just not feasible. If you focus on the natural conditions that exist in desert regions and work with them, you can maximize fine gold recovery. The number one rule is that the drier the soil, the better. Damp soil conditions are very much a hindrance for drywashers. Beyond that, learning the different soil types you may encounter in the desert and how to deal with them can increase your gold recovery. Clay is generally known as a great gold robber, making clay-bound gravels the biggest difficulty to overcome. In most of the placers directly derived from weathering lode deposits, the placers are in ravines, gullies and hillsides with sometimes very little gravels and mostly decomposed fragment of rock and fine silt from the decomposing host rock. Host rock containing a lot of feldspars are most problematic. As feldspar breaks down, it creates some difficult clays and silts that bind fine gold to small rocks and sand with the clay and silt particles forming larger clods. Loamy or sandy conditions are much easier to process with a drywasher than clay-bound material due to the absence of clods and clumps. But if dirt clods are giving you grief, break them down with a large hammer on a canvas tarp, or use a mortar and pestle (dolly pot). Once you are set up to run material, process in short runs before cleaning out the riffle tray (perhaps after every three 5-gallon buckets). Frequent clean ups minimize the amount of fine gold that may creep or walk down the riffle tray with the tailings. This method uses your dry washer as a form of a classifier to screen off larger material while getting rid of much of the fine silt and lighter weight material. Re-running tailings can aid in the recovery of lost gold— especially small gold dust and flakes. The second pass through is usually much quicker than the first time because the material has already been classified. With some placers, especially flat, fine gold, rerunning material can be very lucrative. In places where gold is more coarse and angular, very little gold will like be recovered by running the tailings a second time. You may want to experiment with adding a second layer of cloth to a portion of the riffle tray. Doing so reduces airflow by almost half in that section. In addition to the riffle tray, the void under the riffle tray can collect a sizable amount of really fine gold mixed in with fine silt. No doubt there are going to be losses of gold when using a drywasher to recover fine gold (20 minus mesh down into the 200 minus gold), but the end goal should be to limit those losses as much as possible and these tips should help. Good luck! Learn more about Gold Buddy drywashers here. Nugget of News Blog Sunday, December 01 2013
Dry washers are like highbankers except they do not use water to recover gold. While wet processing is nearly always faster and more efficient, especially for fine gold, dry washers are the best tool for recovering gold nuggets, pickers, and flakes from dry materials in the desert or other areas where water is not plentiful. Keep these tips and tricks in mind when using a dry washer: • Double-check all the "throw away" rocks. Scanning them with a metal detector is a great way to ensure you're not tossing aside gold-laden rocks. Also, don't assume old tailings piles have been totally worked out. This is another time to use a metal detector because ordinary rocks could be laced with gold and completely over-looked by earlier prospectors.
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