'Fool's Gold' Actually Contains a Newly Discovered Type of Real Gold, Scientists Find
The term was often used during the California gold rush in the 1840s because inexperienced prospectors would claim discoveries of gold, but in reality it would be pyrite, composed of worthless iron disulfide (FeS₂).
Ironically, pyrite crystals can contain small amounts of real gold, although it is notoriously hard to extract. Gold hiding within pyrite is sometimes referred to as "invisible gold", because it is not observable with standard microscopes, but instead requires sophisticated scientific instruments.
It wasn't until the 1980s when researchers discovered that gold in pyrite can come in different forms – either as particles of gold, or as an alloy, in which the pyrite and gold are finely mixed.
In our new research, published in Geology, my colleagues and I discovered a third, previously unrecognized way that gold can lurk inside pyrite. When the pyrite crystal is forming under extreme temperature or pressure, it can develop tiny imperfections in its crystal structure that can be "decorated" with gold atoms.
The atoms within a crystal are arranged in a characteristic pattern called an atomic lattice. But when a mineral crystal such as pyrite is growing inside a rock, this lattice pattern can develop imperfections.
