There are several reasons for which a prospector should know about the magnetism of gold. This characteristic can help separate it from the surrounding black sand concentrates and retrieve fine particles.
Gold is not magnetic – in fact, it is diamagnetic (repelled by a magnet). However, this is the case only for pure gold. If it contains iron or other elements from the host rock, it can be slightly magnetic. The diamagnetism of gold can be used in your favor to retrieve it.
Let’s find out everything you should know about this peculiarity of gold.
Table of Contents
Diamagnetism of Gold
Generally, pure gold is not magnetic. This is established by Faraday’s Law of Magnetic Induction. When a material or element is placed in a magnetic field, it will react to the magnetic forces in different ways.
- Some elements, such as iron and cobalt, are highly susceptible to these fields, which will attract them closer. They are referred to as ferromagnetic.
- Elements such as palladium, platinum, or rhodium are considered paramagnetic. The magnetic field will attract them, but not considerably.
- Lastly, pure gold or silver are diamagnetic, which means that the magnetic field will repel them.
In the case of diamagnetic elements, the reaction to the magnetic field will be much weaker than for ferromagnetic elements. Due to the weak response, it might be challenging to notice the reaction of gold particles smaller than one gram.
Additionally, this characteristic of gold is only valid if you are examining a piece of pure gold. If it has been contaminated by other elements, such as iron, that were part of the host rock and attached to the specimen, you might notice that the magnet will attract a piece of gold.
This reaction is due to the strong ferromagnetism of iron that will counteract the weak diamagnetism of gold.
What if a Piece of Gold Is Magnetic?
As we have seen, pieces of gold that are not pure and boast other elements attached to it could be attracted by a magnet. If you notice this characteristic in a piece of jewelry, that could indicate that a portion of pure gold is not so fine and boast only inferior percentages of gold.
Other scenarios in which you could notice gold reacting positively to magnets is in the case of gold nuggets retrieved from lode or placer deposits. Especially when the gold nugget is still coarse, a magnet might attract it. This is because the natural forces have not acted for long on the piece of metal, failing to weather it thoroughly.
Therefore, some elements deriving from the host rock – usually iron or copper – might still be attached to it. In the case of gold nuggets that have been eroded and present smooth surfaces, these might be less magnetic and contain more significant percentages of pure gold.
Using the Diamagnetism of Gold to Retrieve It
The characteristic of gold of being diamagnetic is something that can be used for many purposes, by collectors, prospectors, jewelers, and buyers. Some of the most common uses are:
- Identifying the percentage of pure gold in a specimen
- Whether a specimen contains magnetic elements
- Separating fine gold particles from black sand concentrates
- Distinguishing real gold from Fool’s Gold
- Devise new methods for retrieving gold and perfecting the ones already in use
Gold in Black Sand Concentrates
Black sand concentrates are what will be left at the bottom of your pan at the end of the gold panning process. Many expert prospectors can also pan the material down until only particles of gold remain in the pan. However, if you are in the process of refining your skills, there are other methods you could use to separate such black sand concentrates from potential gold particles.
Black sand concentrates are a mix of elements with a high specific gravity that tends to sink at the pan’s bottom during the panning process. Generally, such a blend is composed[1] of:
- Magnetite
- Hematite
- Titanium
- Zircon
- Rhodolite
- Monazite
- Tungsten materials
- Pyrites (Fool’s Gold)
- Other materials present in the local territory such as gold, silver, and platinum.
Some of these elements, such as magnetite, are highly magnetic, while others, such as hematite and gold, are not. While using a magnet to separate the black sand from gold might not leave you with just gold in your pan, it can help you start classifying the materials and identify gold.
Gold vs. Fool’s Gold
One challenge for novice is distinguishing real gold from Pyrite, also known as Fool’s Gold. This mineral is mainly composed of iron sulfide and presents a similar color and appearance of gold.
Some other characteristics of Pyrite (glitter, low specific gravity, streak, etc.) are also useful in identifying this material. However, for most of these tests, you might need special equipment and knowledge of the characteristics that set these elements apart.
Instead, many prospectors can perform a simple test, just by using a magnet. Indeed, Pyrite is magnetic, a characteristic that can help you quickly set it apart from gold.
Other Methods to Retrieve the Gold
The characteristic of gold of being diamagnetic is leveraged in other ways by prospectors and miners. The feature is used to devise retrieving methods that could separate fine particles of gold from the surrounding streambed material and magnetic black sand.
Examples of this are metal detectors and the shaker table with a magnetic separator. The tables’ movement allows the heavier particles in the mix to fall towards the surface of the table. The magnetic separator will trap most of the magnetic particles, making the identification of gold much more straightforward.
You can learn how to use this recovery tool through the video below.
It is vital to notice that such methods might be pricier for a recreational prospector who practices this activity as a hobby. Below you can find out how to leverage the characteristics of gold through your standard prospecting kit.
Using a Magnet on Your Prospecting Trip
While on your prospecting trip, you might not be equipped with a shaker table with an incorporated magnetic separator. However, other tools[3] can help you achieve the same results without having to incur significant expenditures.
It is essential to notice that the separators below will not work on the non-magnetic elements in the black sand concentrates. Additionally, before using them, it is vital to ensure that the mix is completely dry. If the black sand is wet or moist, you might struggle to separate the elements in it.
SE Magnetic Separator Pick-Up Tool with Quick Release
This tool has a magnetic capacity of 8lb (3.6kg), enough for a prospector to separate most of the elements in a standard gold pan. It is perfect for picking up magnetic objects, shavings, and particles. The quick-release handles can streamline the process, and the lightweight design makes it ideal for carrying with you on any trip.
SE Prospector’s Choice 5 lb. Magnetic Black Sand Pocket Separator Pen
While more expensive, this is the preferred tool by most prospectors. It is waterproof and has a magnetic capacity of 5lb (2.2kg). The quick-release lever and the pen-like design make it the perfect addition to your minimal prospecting kit.
Conclusion
Gold, in its pure form, is not magnetic, also called diamagnetic. This causes gold particles to be repelled by magnets. Prospectors, jewelers, and buyers can leverage this characteristic of gold. In the case of prospectors, the fact that gold is not magnetic can be useful in separating it from surrounding black sand concentrates.
Additionally, this feature can be used as an initial test to distinguish Fool’s Gold to real gold. Everything you need to verify whether you are dealing with pure gold or with specimens boasting other elements is a prospector magnet.