A man panhandling by a stream.
People throughout history have been deceived into thinking they've found gold when they've actually found pyrite, or fool's gold. Even Captain John Smith was fooled; in the early 1600s he sent an entire shipload of pyrite to London thinking it was gold, according to the Utah Geological Survey site. Eventually professional and amateur panhandlers learned to look for certain signs to tell whether they had a fortune on their hands -- or a handful of fool's gold.
Color Depth
Three large gold-colored rocks.
Gold is a metal; pyrite is a mineral, and while they are visually similar, there are significant differences if you know where to look, and test them. Visual clues give the first hint of the authenticity of the nuggets or flakes. Both gold and pyrite are a yellowish, metallic color, but real gold ranges from a golden color to a silvery yellow hue. The yellow of pyrite, on the other hand, is more brassy whether it is a pale or deeper yellow.
Shape and Size
Hands holding a large, golden-colored nugget.
Gold nuggets are not usually very large. It is very rare that cubic gold crystals are found. Octahedral (two pyramids with bases joined) gold crystals are also a rarity. Most often, if it's real gold, you'll find just little flakes or shapeless grains. Pyrite crystals do form cubes, octahedrons and other shapes more often, and sometime have small striations running through them. However, pyrite also can appear as shapeless grains, so there are other methods to test whether you have true or fool's gold.
Smell Test
Pyrite has a sulfurous odor, which smells like rotten eggs. Rub the metal vigorously with something hard, then smell it. If it has an odor, it is probably pyrite. Gold has no odor at all, even after it is rubbed. Pyrite will also give off this sulfurous odor when it is shattered, or thrown against a rock.
Hardness Test
Gold is a soft metal and lacks the hardness of pyrite. You can test which you have by scratching the surface of the mineral with a knife or other sharp surface and then observing. If it it has scratches, you likely have gold. Pyrite does not scratch. The Utah Geological Survey cautions, however, that there is another, very brassy mineral called chalcopyrite that is similar to pyrite -- but is softer and can be cut. Your other tests will weed that mineral out, though. Because gold is soft, it will flatten out or alter its shape when you hit it with a hammer, but it will not break. Pyrite is much harder and your hammer will likely strike sparks from the mineral when you do this test, because of its high iron content.
Tags: fool gold, Geological Survey, gold crystals, hammer will, real gold, shapeless grains
