pyrobitumen
/ˌpʌɪrə(ʊ)ˈbɪtʃʊmɪn/ /ˌpʌɪrə(ʊ)ˈbɪtjʊmɪn/Geology
noun
Any of a class of bituminous hydrocarbons which differ from the bitumens proper in being relatively hard, infusible, and insoluble in organic solvents.
Origin
Mid 19th century (in an earlier sense). From pyro- + bitumen.