What does petrography mean?
Petrography is the branch of geology devoted to describing and classifying rocks. It concentrates on identifying minerals, examining microscopic structure, and interpreting textures, often using thin sections viewed under a polarizing microscope. The discipline is essential in studying igneous, sedimentary, and metamorphic rocks, identifying raw materials used in historical artifacts, and understanding the formation of meteorites or geological deposits. Although petrography overlaps with petrology, it is more specifically concerned with descriptive and microscopic analysis, while petrology additionally addresses the origins and physical processes that produce rocks. The term is most common in academic, geological, archaeological, and conservation contexts. Its combination of careful observation and classification makes it a valuable tool whenever a rock's composition or history must be read from its internal features. Petrography also appears alongside related practices such as mineralogy, which examines individual minerals and their chemical properties.
nounThe branch of geology concerned with describing and classifying rocks, especially through microscopic examination of their mineral composition and texture.
- The geological study and description of rocks, particularly their mineral composition, microscopic structure, and texture.
"Petrography revealed that the dark bands in the rock were layers of volcanic ash."
"Petrography of the meteorite exposed traces of a previously unidentified mineral."
"The course combines petrography with the study of igneous and metamorphic processes."
The plural is uncommon and normally denotes separate petrographic studies or analyses.
"The two petrographies reveal distinctly different mineral assemblages."
Petrography literally means "rock writing": it is the science of reading a rock's minerals and textures like lines on a page.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Where does petrography come from?
Petrography combines the combining form petro-, ultimately derived from Greek words for "rock," with -graphy, from Greek graphein, "to write" or "to draw." Its literal sense is therefore "rock writing," an apt description of interpreting the structure and composition of stone. The English scientific term became established in the early nineteenth century alongside the developing discipline of descriptive geology.
Related word forms
How petrography is actually used
Petrography is formal, specialist vocabulary used primarily in geology, mineralogy, archaeology, and materials science. In archaeological contexts, it may refer specifically to the microscopic study of stone artifacts.
Easily confused with petrography
Petrography primarily describes and classifies rocks through mineralogical and microscopic study, whereas petrology also investigates how rocks form and change.