Petrology (from the Ancient Greek: πέτρος, romanized: pétros, lit. 'rock' and λόγος, lógos) is the branch of geology that studies rocks and the conditions under which they form. Petrology has three subdivisions: igneous, metamorphic, and sedimentary petrology. Igneous and metamorphic petrology are commonly taught together because they both contain heavy use of chemistry, chemical methods, and phase diagrams. Sedimentary petrology is, on the other hand, commonly taught together with stratigraphy because it deals with the processes that form sedimentary rock.Lithology was once approximately synonymous with petrography, but in current usage, lithology focuses on macroscopic hand-sample or outcrop-scale description of rocks while petrography is the speciality that deals with microscopic details. In the petroleum industry, lithology, or more specifically mud logging, is the graphic representation of geological formations being drilled through, and drawn on a log called a mud log. As the cuttings are circulated out of the borehole they are sampled, examined (typically under a 10× microscope) and tested chemically when needed.
Petrogenesis, also known as petrogeny, is a branch of petrology dealing with the origin and formation of rocks. While the word petrogenesis is most commonly used to refer to the processes that form igneous rocks, it can also include metamorphic and sedimentary processes, including diagenesis and metamorphic reactions.
The study of the origin, composition and structure of rock.
The branch of petrology dealing with the origin of igneous rocks.
the branch of science concerned with the origin, structure, and composition of rocks.
The department of science which is concerned with the mineralogical and chemical composition of rocks, and with their classification: lithology.
A treatise on petrology.
the branch of geology that studies rocks: their origin and formation and composition