pet·ro·graph·ic \|pe.trə|grafik, -fēk\adjective orpet·ro·graph·i·cal\-fə̇kəl, -fēk-\ Etymology:petrographic probably from (assumed) New Latin petrographicus, from New Latin petrographia petrography + Latin -icus -ic; petrographical from New Latin petrographia + English -ical : of or relating to petrography • pet·ro·graph·i·cal·ly\-fə̇k(ə)lē, -fēk-, -li\adverb