If you have gotten started gold panning yourself, or just spoken to a prospector, the chances are that you have stumbled across the term “placers” or “placer gold” more than one time. Although the term might suggest that placer gold is very different from normal gold, that’s not the case.
So, what is placer gold? Placer gold is gold that has broken loose from the main lode, as a result of weathering and erosion. Placers can be found both close to and far from the gold lode, depending on the forces at play. One example is placer gold that gets into a river, where it can travel thousands of miles downstream
Placer mining is the by far most common mining activity practiced by hobby prospectors, as the gold doesn’t need to be extracted from hard rock.
Another reason is that placers often lie on the surface, and are accessible to nearly anyone using just hand tools. As a result, most of the gold that was found in the gold rushes of the 1800s came in the form of placer deposits.
So, with placer gold being so popular among miners, let’s look closer at it and then see how you can get started as well!
Table of Contents
The Different Types of Placer Gold
Placer gold can be divided into several types depending on where it’s found. For instance, gold that has just broken loose from the vein and rests in its vicinity is generally referred to as “residual placers”, while gold that has made it into a stream is called “alluvial placer”.
Regardless of the type, the gold is the same. The only thing that varies is how far it has moved, and where it is at the moment. So, let’s look closer at the most common distinctions made when discussing placer gold.
Residual Placers
The first type of placer is the one which has just recently broken loose from the lode. As the host rock is eroded and carried away by wind and water, the heavy gold stays where it is, and can form high concentrations of gold on that very spot.
Eluvial placers
Once the residual placers have moved a short distance from the original vein, they are categorized as “eluvial placers”. Since they often occur on hillsides, they are also called “hillside placers”.
Since eluvial gold has not yet made it into a river or waterway, the gold has not yet been smoothened by the river and its gravels. As a result, eluvial gold has a rougher, more angular shape than gold that has been in a river for a longer period of time.
Alluvial Placers
Once the gold has migrated down the hillside and finally made it into a waterway, it’s categorized as “alluvial gold”. As mentioned above, the water, gravels, and rocks will smoothen the gold by mechanical erosion, and give rise to the smooth appearance we are used to.
Since gold is many times heavier than the other materials found in a river, it will start to concentrate at special locations in the streambed and form paystreaks.
Which Type of Placer Deposits Are the Easiest to Find?
Alluvial deposits must be considered the easiest to start with, as the only piece of equipment you need is a gold pan, Metal detecting, on the other hand, has a steeper learning curve, and in many states, it’s simply easier to find alluvial gold than eluvial or residual deposits.
The by far most mined placer deposits are alluvial placers. Since the waterway has already concentrated the gold, the job of the miner gets much easier, as he or she has to work through much less gravel to get the gold. Most deposits discovered during the gold rushes of the 1800s were, in fact, alluvial placers.
When it comes to residual and eluvial placers, these can contain really high concentrations of gold. However, they are harder to find as there is no river that concentrates the gold for you and provides hints where it might be. However, this also means that eluvial and residual placers were rarely discovered by old-timers, as they didn’t have modern tools at their disposal. The modern prospector equipped with a metal detector stands a much better chance!
Stream Placers: How Placer Gold Deposits Form In Rivers
As mentioned above, the by far most common place to mine for placer gold is in rivers and waterways. And although much gold has been dug out, there still is plenty left to find if you just look in the right places.
So, where do placer gold deposits form in rivers?
Well, gold is really heavy. More precisely, it’s 18 times heavier than water, and 6 times heavier than most other materials in the streambed. In other words, in order to move gold, there must be a rapid and strong flow, which often occurs around spring, when the snow melts off and gets into the active waterways.
When the gold travels down the river, its weight will make it prone to settling as soon as it enters a low-pressure zone. In short, a low-pressure zone simply is a location where the current speeds down and gives the gold a chance to drop to the streambed. This is also where you will find most of the gold!
Here are a few places in a river where low-pressure zones often appear and will cause the gold to settle:
Inside Bends
It’s common to see gold drop off along the inside bend of a river. This has to do with the centrifugal forces at play. Simply put, the water that travels along the farther bend will have to accelerate to cover the longer distance, whereas the flow along the inside bend is going to slow down as the distance to cover is much shorter.
Another thing to keep in mind when it comes to turning and meandering rivers is that the sheer weight of the gold means that it will take time for it to change its path. As a result, gold is more likely than other materials to collide with the benches and get trapped in the process after sudden turns of the river channel.
Behind Boulders
You also want to look out for different types of obstruction such as boulders, where the current loses some speed.
When the water hits such an obstacle, it will create low-pressure zones behind and in front of the boulder where the gold might drop. In case the boulder happens to be in a streak where a lot of gold travels by, some of it is likely to concentrate behind it.
Protruding Outcroppings
Outcroppings that protrude out into the river often serve well as gold traps. Where the gold will concentrate depends on the size and shape of the outcropping, but the following rules generally apply:
If the outcropping is facing upstream, the gold usually concentrates in front of the outcropping.
If it’s facing downstream, the gold is more likely to concentrate behind the outcropping.
_______
If you are interested in knowing more about how gold deposits in rivers, my guide to reading a river for gold is worth having a closer look at!
_______________
Quick Tip: You can often judge how far the gold has traveled from the original source by observing its shape. The softer the edges, the longer time it has spent in the river getting smoothened and polished against gravels and rocks.
Desert Placers: How Placer Gold Deposits Form In Deserts
The way placer deposits form in deserts is a little different, as there is no water available to concentrate the gold. Instead, desert placers form as the wind blows away lighter particles, while the heavier ones stay where they are. With time, the concentration of gold increases, and rich deposits are created.
Desert placers normally stay close to the original gold source, and the gold doesn’t move very much. As a result, gold found in desert placers tends to be quite rough with little signs of wear.
Another characterizing trait of desert placers is that they tend to be quite shallow. The constant removal of light materials by wind and lack of vegetation, makes the gold deposits stay close to the surface. They are seldom more than a couple of feet deep, which makes them perfect for metal detecting. States like Arizona are well-known for their good-sized gold nuggets that lie within depths accessible using nothing more than a small pick or shovel.
How To Mine Placer Gold: Equipment Needed
When mining placer deposits, having the right type of equipment for your type of deposit will make life much easier. Let’s look at what equipment you need to get mining successfully!
Gold Pans
Most used for: All types of placer deposits
The gold pan is used by virtually every prospector as it’s easy to use, lightweight, and has a high gold recovery rate. However, it’s not a production tool, as its capacity is rather limited.
Here is my complete guide to gold panning for beginners
Sluice Boxes
Most used for: Stream Placers
The sluice box is a nice upgrade if you come from using only a gold pan. It lets you process many times more material, in turn making you catch more gold.
For those who don’t know, a sluice box is a long narrow box, equipped with gold traps that is placed in a river or creek. The material is then poured into the device, and the gold gets trapped while the lighter materials flow out with the escaping water.
Metal Detectors
Most used for: Desert placers, residual and eluvial placers
Metal detectors need to introduction. They are perfect when looking for coarser gold and gold nuggets in places where water is scarce. Some prospectors also use them to seek through river benches that have been left dry during the summer.
Here is my complete guide to metal detecting
Gold Dredges
Used for: Stream Placers
A gold dredge is the best production tool available for retail miners. In essence, a gold dredge consists of a motor, a vacuum hose, and a sluice box that sits on floats. The operator then sucks in sand, gravel, and dirt, which goes to the floating sluice box, which in turn separates the gold from the other materials.
Other Tools
Some other tools you will need include:
- Classifiers
- Buckets
- Pick and shovel
How Pure Is Placer Gold?
The fineness of placer gold depends to a large extent on the location where it’s found. Normally, placer gold found in the US has a purity of around 70%-80%. The remaining part is made up of other metals such as silver and copper, or minerals of varying kinds.
Some of the purest placer gold discovered has a purity above 95%. Gold nuggets found in Australia are especially known for their purity.
How Much Is Placer Gold Worth?
When selling placer gold of typical purity, you can expect to get around 70%-80% of the gold metal value. For really beautiful gold nuggets, you can get twice the metal value, or even more!
The worth of placer gold depends largely on three factors:
- To whom you sell: You would be surprised how big of a difference finding the right buyer could make. While a refinery might buy a rare, crystalline shaped piece of gold for just 80% of the gold market price, a collector could pay several times that amount.
- The shape: Beautifully shaped gold pieces are much more attractive and can yield rates several times their actual metal scrap value.
- The purity: Obviously, in many cases, the purity of the gold plays a big role.
_______________________
If you are interested in knowing more about how to sell placer gold, I recommend you have a closer look at my guide to selling placer gold and gold nuggets.
_______________________
Conclusion
Placer gold is the by far the most common type of gold deposit worked by hobby prospectors. Since placer gold has already broken loose from the gold vein, it doesn’t require heavy equipment or machinery to be recovered. A gold pan and a sluice box is a perfect combination that will take you very far!
Happy Prospecting!
