Fool's Gold

The term fool's gold is today used to describe anything that initially appears valuable but eventually turns out to be worthless. In particular it is used when someone has put considerable effort into attaining the worthless "prize".

So where did the term originate? It turns out to have a very specific meaning related to a not very valuable type of rock.

What Is Fool's Gold?

Fool's gold is the informal name given to the mineral iron pyrite, sometimes just called "pyrite". This is a crystalline form of iron sulphide (FeS₂) which has a metallic, golden shine. When studied closely you can see that it is obviously not gold, however when a small speck is poking out of a mine wall then the glint can make it look like gold.

Many old time prospectors and miners used to be fooled by this into thinking they had discovered valuable gold deposits. Often considerable time and energy would be spent on mining the area only to discover that there was no real gold present, just worthless shiny rock. Small amounts of real gold are sometimes found alongside iron pyrite, but that can at best have been a small consolation for the miners who had expected to become wildly rich.

Although fool's gold looks similar to the real thing it can easily be distinguished from the genuine article. Even if they look similar iron pyrite is less hard and more brittle.

What's It Worth?

Is fool's gold valuable? Not really. Iron pyrite is one of the world's most common sulphorous minerals and is far from rare. The main use for it in the modern world is as an industrial source of sulphur.

Although not valuable fool's gold is not totally useless in jewelry - because of its attractive colour it's used in some of the costume pieces you can buy.