Abstract By correlation of various selected physical and chemical properties of heavy crude oils and natural bitumens, an attempt is made to solve classification problems. The criteria used here are, in descending order: viscosity, gravity, H/C atomic ratio, O/C atomic ratio, optical reflectivity, volatiles, and composition. Crude oil and natural bitumen are considered to be petroleum classes; light, medium, heavy, and extra-heavy crude oils as subclasses analogous to light bitumen, tar sands oil, and natural asphalt. Bitumen families are ozokerite, pyrobitumen, asphaltite, and impsonite. Bitumen species are elaterite, wurtzilite, and albertite of the pyrobitumen family; gilsonite, glance pitch, and grahamite of the asphaltite family; the impsonites are called anchi-, epi-, meso-, and kata-impsonites. Subspecies are early or migrated wurtzilites, upper and lower gilsonites, the oxi(dized) variants, “resinic,” “asphaltenic,” and “mixed” subspecies. Misleading or proper names like “gilsonitic” asphalts, ingramite, liverite, tabbyite, and shungite should be used only locally.