What Is Fool's Gold?
Fools gold, chemical name pyrite, is a shiny brass-coloured mineral that almost perfectly mimics the look of gold. The differences between the two metals, however, are significant. Fools gold isn’t nearly as valuable as gold because of its differing properties, so if you’ve found a gold, metallic rock in your backyard don’t rejoice just yet. However, if your miracle find does turn out to be plain old pyrite it’s not all bad news, because fool’s gold has it’s own unique uses and can also indicate the presence of other precious metals in the vicinity. You’d be a fool discount its importance completely!
A Brief History of Fool's Gold
Fool’s gold earned its name from early miners, who’d find the gold-like rock in their pans and mine shafts and mistakenly think they’d just scored a fortune. The mineral was initially hated by prospectors, who associated it with only crushing disappointment, until it was found that pyrite has a value of its own. After this was discovered fool’s gold became an incentive for many early European explorers to journey to North America and cart back the mineral by the ton to Great Britain and France for a profit. This boom eventually died down and pyrite went back to being relatively useless, until the early 1900s when Lawrence Bragg used a sample of the mineral to conduct some of the earliest research on crystalline structures.
What is Pyrite?
Pyrite is a mineral composed of iron and sulphur. Given that iron has a shiny sheen and sulphur is a brassy yellow colour, it’s clear how the mineral often gets mistaken for gold. Pure pyrite has the chemical formula FeS2 and is the most abundant sulphide mineral on earth. Deposits of the crystal are found all over the world, in sedimentary rocks such as limestone and shale, metamorphic rocks like schist and in hydrothermal veins.
What's the Difference Between Pyrite and Gold?
Upon first inspection, you should be able to tell that miracle lump of 'gold' is pyrite if it feels light in your hands and if the surface can’t be scratched, either with your fingernail or with a pocket knife. This is because pyrite is much harder than the notoriously soft and malleable gold. If you want to conduct further tests, try crushing a bit of your find. Pyrite will crumble into a greenish-black powder, while gold power still retains it’s golden colour. Pyrite is also far more brittle than true gold so if you can snap the lump in half you’re not going to be a millionaire today. Sorry.
Soft and malleable
Hard and brittle
Forms a yellow powder when crushed
Forms a black/green powder when crushed
Worth about $1300 per ounce
Worth about $35 per ounce
What are Pyrite's Uses?
Though it’s not as precious gold, pyrite still has plenty of uses. During World War Two the mineral was actively mined for its sulphur content in order to produce sulphuric acid. Today, pyrite can be used as a gold substitute in making jewellery and is also used in some car batteries. Some pyrite deposits can also contain up to 0.25% gold by mass and can thus be broken down to extract the more lucrative metal. When struck together, lumps of the mineral can produce a spark the can be used for lighting fires, hence the inclusion of pyr- (greek: fire) in the name. Because of this, fool’s gold is occasionally used in flintlock firearms. On a more modern scale, pyrite has been found to have semi-conductive properties and is currently being investigated as a potential material to make solar cells from. Fool’s gold can also be a sign that a deposit of real gold or even copper may be close by, and can thus be used as a kind of indicator for prospectors when they’re deciding where they should be mining.
Fool’s gold is a relatively common mineral that, unfortunately, isn’t as valuable as gold. To the untrained eye the two substances can seem identical, but pyrite is actually much harder and more brittle than gold and forms a black/green powder when crushed. However, if you’ve discovered a deposit of fool’s gold in your backyard don’’t despair just yet, because the mineral has its own uses and can also indicate that a deposit of cooper or true gold is close by.
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© 2018 K S Lane