Petrology

n. study and research of rocks

Petrology (from Greek: πέτρα, petra, rock; and λόγος, logos, knowledge) is a field of geology that focuses on the study of rocks and the conditions on which they form. The word lithology once was approximately synonymous with petrography, but today lithology is essentially a subdivision of petrology focusing on macroscopic hand-sample or outcrop-scale description of rocks.
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(n.)
The department of science which is concerned with the mineralogical and chemical composition of rocks, and with their classification: lithology.
  

(n.)
A treatise on petrology.
  

Noun
1. the branch of geology that studies rocks: their origin and formation and composition
(hypernym) morphology, geomorphology