While prospecting for gold, you might have found black sand. These types of concentrates have been deemed to be a sign that gold is nearby, but this is not always the case. Oppositely, gold is often found within black sand concentrates.
Black sand is found with gold because it is composed of the heavier elements in streambed materials. Just like gold, these elements boast a high specific gravity, which causes them to behave similarly when free and deposit in the same locations.
Let’s find out more about the relationship between black sand and gold particles!
Table of Contents
What Is Black Sand?
Black sands are concentrates of heavy materials that can be found in the streambed. These elements can be found near most creeks, rivers, or streams, but the composition of the concentrate might differ.
Usually, black sand concentrates are a blend of commonly found elements, such as magnetite, hematite, pyrite (Fool’s Gold), and copper.
These elements all boast high specific gravity, which causes them to sink to the bottom of the streambed when the current is not strong enough to carry them along.
Other elements such as quartz and clay, instead, are characterized by a low density, which causes them to drift along with the stream’s current.
While gold is one of the elements usually found in black sand concentrates, not all black sand will include gold in its mix. Indeed, gold can be found only in some specific locations when the right conditions are in place.
Elements Commonly Found in Black Sand
As we have seen, black sand includes several elements commonly found in the streambed. While these might differ, they all boast a high specific gravity, high density, and – frequently – a dark color.
Not all the material present in black sand concentrates are magnetic or reacting to magnetic fields. However, some of them, such as magnetite, are.
Therefore, some prospectors use a black sand magnet to complete a first separation stage to separate gold from black sand.
Below we have listed the most common elements in black sand together with their specific gravities.
- Tungsten (19.25)
- Pyrite or Fool’s Gold (5)
- Titanium (4.5)
- Zircon (4.7)
- Magnetite (5.6)
- Hematite (5.26)
- Rhodolite (4)
- Monazite (4.6 – 5.4 depending on its composition)
In comparison, clay, a light material found in the streambed, has a specific gravity of 2.70 to 2.80, depending on its composition.
Of course, in the right conditions, other elements, such as gold and platinum, will also populate black sand concentrates. However, this will happen only happen in certain locations in areas that are naturally gold-bearing.
With that said, black sand is a useful gold indicator that tells us where the gold is most likely to be found, if there is any nearby.
Where To Look For Gold (and Black Sand)
Ultimately, gold is found in black sand because the two elements behave similarly when free. This is because gold and black sand both are among the heavier elements in the streambed, and therefore will take on a similar path in the river, and end up at the same place.
Now, understanding the path that gold follows while traveling along a streambed is essential knowledge for any prospector.
At its core, there are two critical aspects to consider when mapping potential gold deposits along a streambed.
- Heavy elements will take the shortest route.
You will notice bends and curves when you are following the path of a stream, creek, or river. And since gold is so heavy it will result in the following:
- Generally, gold, just like other heavier materials, will follow the shortest path along this route.
- It will travel near the shorter sides of bends, avoid the curvature as much as possible, and generally go on a straighter line.
Therefore, if you plan to pan or sluice for gold along a stream, you should set up your equipment on the inner side of the bends, not on the long one.
This strategy allows you to collect streambed material that is more likely to have gold or – at least – heavier black sand concentrates.
2. The locations with the best chances are the ones where the current slows down.
Streams and rivers can travel for miles, and their course is subjected to changes caused by the landscape and geological formation. Along the river course, you are likely to find instances where the high specific gravity of gold and black sands element would have caused them to sink to the bottom.
These instances happen, for instance, when the course of a river is fast-flowing and suddenly broadens or deepens and slows down as a result.
As the current becomes weaker, it is not able to push gold and other heavy particles along. This will cause them to sink to the bottom of the streambed, where they are likely to remain until someone comes and picks them up.
You can identify these locations by reviewing local topographic maps or by speaking with other local prospectors.
My full guide to reading a river for gold is a great resource if you want to learn more about where gold is likely to end up in a river.
Extracting Gold From Black Sand
If you have been panning or sluicing for gold, you might have some concentrates to examine. If these are composed of heavy elements and retrieved from gold-bearing locations, you shouldn’t be surprised to find gold in it. However, in many cases, the gold might come in its fine form, requiring fine-tuned techniques to be captured.
A finishing pan with small riffles is perhaps the most widely used method for separating gold from black sand. However, it requires you to be gentle while panning, and you have to work through the concentrates several times to retrieve most of the gold. For many prospectors I know, this is an activity they enjoy during the colder months of the year.
There are several other effective tools that can be used to capture even the tiniest gold specks. My full guide to separating gold from black sand deals with the most commonly used methods!
Lastly, it is recommendable to complete the finishing stage of prospecting in a controlled environment where there is a lower risk of losing gold particles in the surroundings. You should never pan your concentrates in a river, as any gold particles that slip out of the pan will inevitably get lost.
Conclusion
Generally, gold is associated with black sand concentrates, while black sand concentrates not always include gold. Indeed, black sands are much more common than gold, meaning that they can be found in more locations.