the branch of petrology that deals
with the description and classification of rocks, esp. by means of examination
under a microscope
Webster’s New World College Dictionary, 4th Edition. Copyright © 2010 by
Houghton Mifflin Harcourt. All rights reserved.
Derived forms petrographer (peˈtrographer)
petrographic (ˌpetroˈgraphic) (ˌpɛtroʊˈgræfɪk
adjective or ˌpetroˈgraphical