it is very common to have all three types of bituminite in organic-rich sedimentary rocks, however, the modal percentage of bituminite type varies. typically type i bituminite is found to be much larger than other types and exude a negative alteration when irradiated with blue light. type ii is determined by its yellowish or reddish-brown fluorescence and its occasional oil expulsions when irradiated. type iii, the rarest kind of bituminite, appears dark grey under a reflected white light, however, lacks fluorescence. it is also distinguished by the fine granular structure and its association with faunal relics.