the GNU version of the Collaborative International Dictionary of English
n. One who is versed in petrology.
The Century Dictionary and Cyclopedia
n. One who is skilled in petrology.
Word Usage
"Chatting to others in her office I found that one off them was ex-Birkbeck and the other informed me that the igneous petrologist might indeed now be interested in my project as she has become obsessed with meteoritics - this is useful info."