Is Gold Magnetic?

by Christopher Peters | Apr 29, 2024

You might be wondering if gold is magnetic. In short, pure gold is not attracted to magnets. However, there are interesting ways it interacts with magnetic fields, especially on a very small scale.

What is Gold?

Gold, with the symbol Au and atomic number 79, is a precious metal that has been cherished for thousands of years. It’s widely used in jewellery and as currency, and you’ll find it in nearly every home. Gold is not just valuable for its beauty; its excellent ability to conduct electricity and its resistance to tarnishing make it vital in manufacturing electronics and medical devices.

Types of Magnetism

To better understand gold’s relationship with magnets, it’s helpful to know about the different types of magnetic materials. There are three main types:

Ferromagnetic materials: These are strongly attracted to magnetic fields. Common examples include iron, nickel, and cobalt.
Paramagnetic materials: These materials are attracted to magnetic fields, but the attraction is much weaker than in ferromagnetic materials. Examples include aluminium, pyrite (also known as fool’s gold), and platinum.
Diamagnetic materials: These materials actually repel magnetic fields, which means they are not attracted to magnets. Gold and silver are good examples of diamagnetic materials.

Gold is diamagnetic, meaning it weakly repels magnetic fields. When the magnetic field is removed, gold does not retain any magnetism.

Why Is Gold Not Magnetic?

To understand why gold isn’t magnetic, it’s helpful to start with the basics of magnetism. Magnetism comes from the movement of electrons in atoms. In some materials, electrons are unpaired and act like tiny magnets. When these unpaired electrons align in the same direction, they generate a magnetic field.

Gold, however, behaves differently. Each gold atom has 79 protons and roughly the same number of electrons, which are free to move and interact with nearby gold atoms. This movement allows the electrons to pair up with those from other atoms, neutralising their magnetic effects.

As a result, gold doesn’t attract magnets. Instead, it exhibits a weak form of magnetism known as diamagnetism, meaning it creates a tiny magnetic field that actually opposes an external magnetic field. This effect is so slight that it’s usually only detectable under sensitive laboratory conditions.

Are Gold Alloys Magnetic?

Gold alloys are combinations of gold with other metals. Pure gold, or 24 karat gold, is very soft and malleable, which makes it ideal for jewellery making but also prone to scratches and bending. To enhance its durability, gold is often mixed with harder metals to form stronger and more resilient alloys.

The magnetic properties of these gold alloys can vary depending on the metals used. For instance, mixing gold with a ferromagnetic material like iron could introduce magnetic characteristics. To significantly alter the magnetic properties, about 20% of the gold would need to be replaced with a ferromagnetic material. This applies to all types of gold, including 18k, 14k, 10k, and even white gold.

Because of these variations, using a magnet to test the authenticity of gold alloys is not reliable and may lead to incorrect conclusions.

Can Gold Have Temporary Magnetism?

Yes, gold can interact with magnetic fields, but this interaction is quite subtle. When exposed to a very strong external magnetic field, the electrons within gold atoms may partially align with that field.

It’s important to understand, though, that this effect is both temporary and very weak. It doesn’t make gold magnetic in the usual sense. Instead, it creates a slight diamagnetic effect. Diamagnetism means that the electrons in the gold offer a small resistance to the external magnetic field, which generates a tiny opposing magnetic field. However, this resistance is so minimal that it usually goes unnoticed in everyday circumstances.

Can I Use a Magnet to Test if My Gold Is Real?

Pure gold isn’t attracted to a magnet. So, if a magnet picks up your gold item, it is impure, gold-plated, or not gold at all. However, using a magnet to check for gold purity has its limitations as the materials often mixed with gold to reduce its karat rating, like copper or silver, aren’t magnetic either. This means a magnet won’t always help you confirm if your gold is real.

One way to understand the purity of gold, you should look at its karat rating. The karat system measures gold’s purity, with 24K indicating 100% gold. As the karat number decreases, more other metals are mixed in. For instance, 18K gold is 75% gold, while 14K contains 58.5% gold. These metals can include copper, silver, or palladium. If a significant amount of magnetic metal is present in the alloy, the item might respond to a magnet.

For a more accurate assessment of gold purity, consider other methods such as checking for hallmarks, performing acid tests, or consulting a reputable jeweller. These approaches provide more reliable results than a simple magnet test.

Are Gold Nanoparticles Magnetic?

New research from 2004 has revealed some fascinating insights into how gold behaves at extremely small scales, such as those seen in nanoparticles. At this tiny size, the behaviour of electrons in gold may show signs of paramagnetism, which is quite different from what we see in bulk gold.

This unique behaviour is linked to how electrons pair up. In the tiniest gold clusters, consisting of just two atoms, calculations suggest that the electrons remain unpaired rather than pairing up. As these clusters grow larger, this tendency to stay unpaired weakens.

Interestingly, Einstein’s theory of relativity also comes into play here. Gold atoms are large, and their outermost electrons move around the nucleus at incredibly high speeds. According to relativity, this high speed affects the electron’s behaviour, causing it to stay closer to the nucleus and become more stable.

This stability of the unpaired electron might explain two key characteristics of gold:

Gold’s Low Reactivity: The stability may help to explain why gold is so resistant to tarnishing.
Magnetic Nanogold: The behaviour of this unpaired electron in nanoparticles could be related to the weak magnetism sometimes observed.

Overall, this research highlights how the size and structure of gold nanoparticles can influence their magnetic properties, with the surprising influence of relativity playing a role.

FAQs

Are All Gold Alloys Magnetic?

The magnetism of a gold alloy depends on the metals it is mixed with. For example, gold mixed with non-magnetic metals like silver will not be magnetic. However, if it’s alloyed with magnetic metals like iron, the alloy could show magnetic properties.

Can Pure Gold Be Attracted To a Magnet?

No, pure gold is not attracted to magnets. If a magnet sticks to a gold item, it suggests that the gold is not pure or it might be mixed with other magnetic metals.

Can Gold Be Magnetised Permanently?

No, gold cannot hold a permanent magnetic field. It does not retain magnetism like some other metals.