PYRRHOTITE SPECIMENS

Pyrrhotite is an iron sulfide mineral that's distinguished from the closely related mineral troilite (FeS) by its variable iron deficiency. It typically occurs in massive, granular, or tabular forms and displays a metallic bronze to brassy-brown color that commonly tarnishes with exposure. Pyrrhotite forms in a variety of geological environments, particularly in mafic igneous rocks, hydrothermal veins, and metamorphosed sulfide deposits, where it is often associated with minerals such as pyrite, chalcopyrite, pentlandite, and sphalerite. One of its more interesting properties is magnetism: certain iron-deficient varieties are strongly magnetic, while others exhibit much weaker magnetic behavior. Although sometimes overshadowed by more visually striking sulfide minerals, pyrrhotite is geologically important and can occur as a significant component of nickel, copper, and other metallic ore deposits.