I have been intrigued by this specimen for a little while. It is not even an important specimen. All that is known is that it is of the Carboniferous Period. Its provenance and even exactly what it is are unknown. However, what immediately struck me was the beauty of the form of the golden-coloured pyrite. Under progressively higher magnification, what I had originally thought might be the veins of a seed-fern leaflet became transformed into a tongue of fire, or matted straw. The original plant material was lucky enough to be buried quickly under anaerobic conditions, and over millennia, some of its organic material has become transformed chemically into pyrite, mimicking precisely the original organic form.
Joy Irving, Mineralogical Collections