We have all heard about the gold rushes of the 19th and 20th centuries when prospectors flooded rivers in search of the lustrous metal. Indeed, a lot of gold was recovered from rivers back then. Even today many rivers see a lot of mining activity, and there are gold miners who even can make a living panning for gold!
But how did all the gold end up in rivers, to begin with? Gold can be found in rivers because they flow through gold-bearing grounds. The gold, which comes from eroded, exposed gold veins, is picked up by the river and can be transported thousands of miles downstream. As a result, gold in rivers can be found far away from the original source.
While this is the simple answer there is a lot more to it! In this article, we’ll be exploring how gold finds its way into rivers, and how miners take advantage of active waterways to do a lot of the heavy work for them! Quite interesting, isn’t it!
Let’s start with a more detailed look at how gold gets into rivers!
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How Gold Gets Into Rivers
To understand how gold goes from being stuck in the host rock to getting picked up and transported by a river, we need to have a look at the process form the very beginning.
Phase 1: Lode Gold Becomes Placer Gold
Most of the gold that exists on earth resides in veins that can be found in hard rock. These are formed as a result of hydrothermal processes deep inside the earth’s crust, where hot acidic solutions dissolve any gold it comes in contact with and brings it up to the surface rock layers. As the solution cools off, the gold deposits inside cracks inside the host rock, and creates what we know as lode gold.
As you probably know, all rock that’s exposed to the elements will tear down eventually in a process called erosion. As the rock is slowly eroded, the gold that’s contained inside is released and falls to the ground. As soon as this happens, the gold changes name from lode gold to “placer gold”.
Phase 2: Placer Gold Travelling Downhill
Once the gold has broken loose from the main lode, it will start to move downhill with help from occasional heavy rains. This is also the process that will eventually make sure that the gold finds its way into smaller drainages that will help transport the gold towards a larger river. Of course, given that it doesn’t stumble upon the big river right away!
As soon as the gold hits the river, it gets pounded and polished by the various types of gravels and sands and will take on the polished shape we are used to. The roughness of the gold can, therefore, be used to give you an idea about how long the gold has traveled from the original source.
Ancient Riverbeds: Another possibility
Now, in some cases, the process in which rivers are fed with gold might involve a second step, namely ancient river beds.
In short, ancient river beds are the remnants of old rivers that no longer exist. Throughout their lifespan they might, just like modern rivers, have collected significant amounts of gold, that now lie deposited in the dried out and often quite well hidden ancient riverbeds.
In some cases, a modern river might cut into ancient riverbeds and take the gold with it. In other words, this presents a slightly different gold source.
Does Every River Contain Gold?
In theory, every river does continue gold, but in reality, most of them will have too low concentrations to be worth considering for mining purposes. In fact, in most rivers, the amount of gold will be so little that it’s not even visible!
In order to know what rivers are worth visiting, you need to study the geology and history of the area. My complete guide to prospecting is an excellent resource for those who want to learn more about how they can get started!
How Rivers Make Gold Mining Easier
As you might have noticed from the explanation above, gold can travel quite a distance downhill before it ends up some kind of waterway. And if that’s the case, you may ask why we don’t just pick it up before it has made it into the river and got mixed with other sands and gravels.
Well, there are those who use metal detectors to look for the so-called hillside placers. And since metal detectors weren’t available during the gold rushes of the 19th century, very few hillside placers were discovered, and remain untouched to this date.
However, there is one reason why gold miners aren’t abandoning rivers for hillside placers in masses, namely its ability to concentrate gold into easily recoverable paystreaks and gold pockets.
How Rivers Concentrate Gold
Even though rivers can stretch across incredibly distances and pass through countless gold-bearing locations, the amount of gold that gets carried away remains tinywhen compared to the total volume of the rest of the streambed materials. If the gold was just evenly mixed up with the rest of the streambed material, the concentrations would be so low that most placer mining operations wouldn’t be able to turn a profit.
Now, the flow of the river plays a crucial role not only when it comes to transporting the gold downstream, but also to separate gravels and materials by weight and size. In simple terms, light materials will easily get carried away by the river current, while the denser materials such as gold are heavy enough to withstand the current and remain in the same spot. With time, in the right locations, gold concentrations will increase manyfold and sometimes create incredible rich pockets of fine gold and even gold nuggets!
This is especially true in spots along the bedrock that offer some type of protection from the current. For instance, gold often finds its way into crevices and cavities where it remains protected from even the most violent of flood events. At the same type, lighter materials are flushed out at regular intervals, creating the perfect conditions for incredibly rich gold pockets.
Of course, gold will move as well if the current is strong enough. This is often the case in spring, when massive volumes of melt-water drastically increase river flows to such a degree that even larger nuggets are thrown around and deposited at new locations.
How Rivers Form Pay Streaks
The last way in which rivers concentrate gold also has to do with the size and weight of different materials. Put simply, heavier materials will react more slowly to turning river channels, and therefore take on a path different to that of lighter materials.
For instance, if the river goes into an S-turn, really light gravels won’t have much of an issue maneuvering the turn. Gold, on the other hand, will be too heavy to quickly change its direction of travel, and will subsequently take on a path different to that of the lighter sands and gravels. This means that if the river slows down enough for the gold to settle, it will do so along the unique path that gold was traveling at that moment, and form so-called pay streaks along that path.
If you want to learn more about how to discover paystreaks, I recommend my full guide on how to find pay streaks. There you will find everything you need to know!
Conclusion
In this article, we have looked closer at how gold finds its way into rivers. As you see, rivers stretching thousands of miles through gold-bearing locations not only work as gold conveyor belts, but also concentrate the gold into much more easily recoverable deposits. This is the reason why rivers remain the first choice of many prospectors when it comes to places to prospect in.
If you want to learn more about finding gold in rivers, we have a lot of resources available that will teach you the necessary skills! Here are three of them:
