Pyrite, FeS2 an iron sulphide, is the most common sulphide mineral. It's distribution is widespread, and it is found in all types of rock. It is also a very common component of hydrothermal mineral deposits. The origin of this specimen is unknown, but it is worth keeping as a type specimen. It is about 75% massive, with an aggregate of small. often intergrown cubic crystals in the remaining 25%