The Collaborative International Dictionary
Petrologist
Petrologist \Pe*trol"o*gist\, n. One who is versed in petrology.
Wiktionary
petrologist
n. A geologist who specializes in petrology
Usage examples of "petrologist".
Karaman, the petrologist, sat in the laboratory swirling a dark and tarry liquid about in a glass flask.
Like photogeologists, for instance, who work from photographs, and petrologists, who treat their rocks like lab specimens, and geochemists and geophysicists.