Most natural bitumens also contain organosulfur compounds,  Nickel and vanadium are found at <10 parts per million, as is typical of some petroleum.
mˈoʊst nˈætʃɚɹəl bɪtˈuːmɛnz ˈɔːlsoʊ kəntˈeɪn ɔːɹɡˌænoʊsˈʌlfɜː kˈɑːmpaʊndz,  nˈɪkəl ænd vænˈeɪdiəm ɑːɹ fˈaʊnd æt tˈɛn pˈɑːɹts pɜː mˈɪliən, ˌæzˌɪz tˈɪpɪkəl ʌv sˌʌm pətɹˈoʊliːəm.