We have been attempting to educate people for some time on the old assumption that pyrite is just fools gold. This adage is almost an old miner's joke on the rest of the population. Truth be told, there is no gold in pure iron pyrite, however, more than 99 times out of 100, there is significant gold in pyritic deposits. Also, the presence of pyrite, especially in western US deposits, is a huge indicator of gold presence.
Consider how many mines you have been to, large mines, where pyrite is present. Do you think that's just a coincidence? Its not, Miners have long known that if you find pyrite, you aren't far from gold. Large mines across the west have considerable amounts of Pyrites in their waste piles. A testament to the minerals removed as they dig out the gold.
The Ophir Hill mine in Ophir, Utah is a prime example of this. Massive tailings piles run out to the highway. The tailings glitter and shine in the sunlight with pyrite cubes. Its similar across the country. To go one extra step, find pyrites on quartz and you are golden, literally.
As final proof of this, Ive attached a list of links, all discussing gold content in pyrites. Even a few pictures.
So the next time someone tells you they found some fools gold, reassure them that its worthless, then be sure to find out where they found it!