Pyrite has been known as “fool’s gold” for quite a while now. It is an iron sulfide (FeS2) and has a brassy appearance that causes people to confuse it with gold. Pyrite is found all over the world, often in quartz veins and sedimentary and metamorphic rocks. It is a very common mineral and forms cubes, octahedrons and pyritohedrons.

The pyritohedral shape is actually named after the mineral pyrite and is basically an irregularly shaped dodecahedron. We have a beautiful specimen in the Dice Mineral Museum with pyritohedral crystal faces, so you should stop by and check it out!

Another awesome fact about pyrite is that is has a polymorph. Polymorphs are almost like fraternal twins. They are made out of the same stuff, but look different. Marcasite is the polymorph, or “fraternal twin,” of pyrite. They are made out of the same stuff, FeS22, but they have different structures.

Marcasite often forms thin, flat, tabular crystals in really cute bunches that look like cockscombs. It is also more brittle than pyrite. Speaking of brittle, amateurs can often tell the difference between pyrite and gold by their hardness. Gold is very soft and malleable, with a hardness of 2-2.5, and it is bendable. Pyrite is much harder, 6-6.5 on the Mohs hardness scale, and it is very brittle. We have plenty of beautiful samples in the Dice Mineral Museum, and we hope to see you there!