Funginite is a maceral, a component, organic in origin, of coal or oil shale, exhibiting several different physical properties and characteristics under particular conditions; its dimensions are based upon its source and place of discovery.[1] Furthermore, it is primarily part of a group of macerals that naturally occur in rocks containing mostly carbon constituents, specifically coal. Due to its nature, research into the chemical structure and formula of funginite is considered limited and lacking.[2] According to Chen et al. referencing ICCP, 2001[3] (International Committee for Coal and Organic Petrology), alongside the maceral secretinite, they "are both macerals of the inertinite group, which is more commonly known as fossilized charcoal, and were previously jointly classified as the maceral sclerotinite".[2] In the scientific community, the discernment between the two does not remain entirely clear, but there are slight particular and specific differences in regards to the composition between both.[2] It is also the product of fungal development on these carbon rich sedimentary rocks.
Resulting from its fossilized roots composed of fungal spores and similar material, funginite quantity as an inertinite has a direct correlation to instances of natural wildfires that occurred during the Cenozoic Era approximately 60 million years ago to the present (see chart), ranging from the Paleogene through to the Quaternary.