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! Sunday, July 14 2019
Alluvial gold refers to tiny gold flakes that come to be through water erosion and movement. In geology, alluvium The alluvial environment is a very complex one, with many natural forces competing with each other. The forces that lay down gold are a summation of many flood water events of varying intensity that cause the reworking of sands and gravels. Between major flood events, water naturally flows along the already created path and typically the gold present in the gravel or on the surface will not move much. But the larger flooding events can change the drainage routes and even the river’s shape. Some curves can be shut off from the stream and bypassed. Where the water speed decreases, gravels will drop out of suspension, creating alluvial pay streaks that are typically located along and near the riverbed. To identify where a pay streak might be located, take the flow of the waterway into consideration. The most productive streaks are formed as a result of major floods that are significant in terms of both water flow and intensity of erosion. Greater amounts of gold are present here as compared to regular gravels. Pay streaks tend to possess a comet-like form. At the “head” or “heart” is found the richest concentration of gold. At this location, the gravel is coarser and the sandy and silty fraction is much less. This little bit of silt is present only for a few centimeters on the surface, laid down in the last phases of the flood as the silt is dropped. The gold in these gravels is typically small flat flakes, with maybe a small picker or two. As gold prospectors, our objective is to learn to read a stream and recognize the pay streaks it contains. Think about where you are going to dig before you start and then repeatedly test the gravel you are processing. It is important to consider the presence, form, and depth of the bedrock on which the water and all the alluvial gravel deposits are sitting. In many cases, the gold will naturally concentrate in the lowest part of the riverbed, making a gold-rich path. During high water events, much of the gold is picked up and put back into motion, which leads to forming new pay streaks. Some will be laid back down along the low line of the stream, but may also end up a little farther downstream. The gravels in contact with the bedrock or false bedrock base are often the richest. The same facts apply to the alluvial pay streaks that are formed on gravel bars— the lowest level of the gold-bearing gravel is normally the richest. The alluvial environment changes over time. Alluvial pay streaks generated 100 years ago could become buried, then subsequently be eroded and exposed again. The erosion might be in part or in total, generating a new series of paystreaks further downstream. Pay particular attention to large boulders and trees. Obstacles like these may partially block the water flow and provide an opportunity for increased gold concentrations, especially behind the obstructions. If there are fissures, holes or natural traps in the stream, be sure to sample these areas, too. Although high water events are sporadic, when you do find a paystreak caused by one, it can be a very productive spot. Stick with it and keep in mind most are small and narrow and best worked by hand with a sluice and gold pans. Nugget of News Blog     |
is loose sediment which has been eroded from a primary source, transported and further eroded by water, and redeposited. Since gold is extremely dense, it is easily trapped alongside other dense alluvial particles. The bits of gold found in these deposits of alluvium are called “alluvial gold.”|
Nugget of News Blog |