This piece displays the classic “coffin-style” habit of pyrrhotite, a metallic iron sulfide mineral. The smaller of the two main crystals is actually doubly-terminated, and the bronze-colored specimen elegantly shows off this feature. Santa Eulalia is famous for its exemplary Pyrrhotites. Historically, the district was one of the most, if not the most, significant sources of quality Pyrrhotite specimens till the end of the 1980s, when material from Dal'negorsk, Russia hit the market at the end of the decade and made Mexican specimens more affordable. This is exemplary for what it is and MUCH more rare than any similarly sized example of the species from Dalnegorsk, for example.