Fool's gold

Iron Pyrite, also known as fool’s gold, is a sulphide mineral that has gained infamy throughout history for its resemblance to gold. With a brass-yellow hue, Pyrite has fooled many a prospector into believing they had found their fortune, only to later realise their mistake. The deceptive appearance garnered the name of fool's gold, but as science has progressed over the years fool's gold has been found to have many uses, even if it remains less valuable than the real thing.

Image courtesy of Didier Descouens via Creative Commons.

What is fool’s gold?

At it's simplest, fool's gold is a mineral known as Iron Pyrite. Pyrite has a number of mineral variations such as molybdenite and arsenopyrite, but it is Iron Pyrite that is specifically known as fool’s gold. With a chemical formula of FeS2, iron disulphide is the most common sulphide material on Earth.

Prospectors would often curse Pyrite for the brief moment of hope and subsequent disappointment it gave them. This hatred was somewhat unfair though as Pyrite can sometimes be found with small quantities of real gold and did have some value, albeit much lower. Gold and arsenic occur within certain Pyrite formations, and the real gold can still be extracted.

Iron Pyrite is highly reactive when exposed to the Earth’s surface. Air and water react with the sulphates present and produce sulfuric acid. This can lead to acid rock drainage in Pyrite mines and the material has to be carefully managed to avoid toxic leakages into the nearby environment.

Fool’s gold or real gold?

Despite its name, the differences between fool's gold and real gold are actually fairly apparent. Gold is a very dense material compared to Pyrite and holding even a small lump of either metal in your hand will feel very different. Non-destructive tests like this are great ways to check if you’ve found real gold without damaging it.

Another simple, but more destructive, way to tell if you have fool's gold or real gold will be to test the softness/malleability of the metal. Gold is very soft and can be easily dented or marked with a fingernail or knife. Pyrite is much harder and will not be scratched as easily, if pressure is applied it will break rather than bend as gold would.

Pyrite

Although undoubtedly of lower value than gold, Pyrite does have a number of properties that make it useful to this day, and potentially beyond.

The name Pyrite is derived from the Greek word for ‘of fire’ or ‘in fire’ and was grouped with a number of rocks that would produce sparks when struck with steel. This links to Pyrite's first major use; as a source of ignition in early wheel-lock firearms.

Today, Pyrite is used for a number of technologies, including lithium batteries and crystal radios. It has been suggested that Pyrite could be used for photovoltaic cells in solar panels, thanks to its abundance and low value. With solar energy use growing, Pyrite could see its demand increase if its use was deemed viable.

Recently, scientists have postured that fool's gold may even contain tiny particles of real gold. This could further help expand the uses for Pyrite as an additional source of real gold as resources slowly dwindle.

Pyrite cost

Unlike gold, Pyrite is not mined as the primary goal of any mining operation and isn’t sold in specific weights like gold bullion. Instead, Pyrite is usually bought in crystal formations. Pyrite can form in quite unique and visually appealing ways such as the cubic formation shown below, making for interesting artistic applications.

Image courtesy of Carles Millan via Creative Commons.

Though quite cheap, as noted above, Pyrite can contain real gold and, with the price of gold high, even a small amount can increase the value of Pyrite considerably if extracted.

All gold bought and sold by BullionByPost is tested rigorously by a combination of XRF laser and digital weight scales to ensure its authenticity.