The pyrrhotite and galena here are intricately intergrown, having formed together, which I have seen before from this locality - though specimens such as this are rare. You can see the characteristic terraced, blocky form of the pyrrhotite compound crystal, with the galenas being small crystals interspersed. There is some sphalerite present as well. This Mexican pyrrhotite has a distinctively different patina from those from elsewhere, such as Dal'negorsk, with a yellow ochre color and shimmering luster.