/pi trol"euh jee/, n.the scientific study of rocks, including petrography and petrogenesis.[1805-15; PETRO-1 + -LOGY]
* * *Scientific study of rocks, including their composition, texture, and structure; occurrence and distribution; and conditions of origin.Petrology is concerned with all three major types of rocks: igneous, metamorphic, and sedimentary. The subdiscipline of experimental petrology involves synthesizing rocks in the laboratory to ascertain the physical and chemical conditions under which they form. The subdiscipline of petrography is concerned primarily with the systematic study and description of rocks using a petrographic microscope.
* * *▪ sciencescientific study of rocks that deals with their composition, texture, and structure; their occurrence and distribution; and their origin in relation to physicochemical conditions and geologic processes. It is concerned with all three major types of rocks—igneous, metamorphic, and sedimentary. Petrology includes the subdisciplines of experimental petrology and petrography. Experimental petrology involves the laboratory synthesis of rocks for the purpose of ascertaining the physical and chemical conditions under which rock formation occurs. Petrography is the study of rocks in thin section by means of a petrographic microscope (i.e., an instrument that employs polarized light that vibrates in a single plane). Petrography is primarily concerned with the systematic classification and precise description of rocks.Petrology relies heavily on the principles and methods of mineralogy because most rocks consist of minerals and are formed under the same conditions. Also essential to petrological research is the careful mapping and sampling of rock units, which provide data on regional gradations of rock types and on associations unavailable by other means.
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