Petrology is one of the important branches of geology which deals with the study of rocks. Generally a rock is an aggregate of various minerals. The rocks in turn are classified in to three main divisions namely

a. Igneous rocks
b. Sedimentary rocks and
c. Metamorphic rocks

      Mineralogy is the study of minerals. A mineral is usually a natural inorganic substances having a definite chemical composition and characteristic atomic structure. The minerals are indispensable to man. Moreover minerals are the backbone of our modern industries.

    The term "palaeontology" is the study of ancient life such as fossils. Fossils are the recognisable remains of animals and plants which lived in the past geological ages and preserved  in the rocks of the earth's crust by natural process. The various types of fossil exhibits are mainly collected from Ariyalur-a town about 70 Kms from Tiruchirapalli. A gigantic ammonite fossil, huge fossil elephant skull and rhinoceros fossil attract the attention of most of  the visitors in the geology gallery. Huge fossil wood from Tiruvakkarai is also exhibited in the museum open air garden with fencing.

    The economic geology deals with the economic aspects, which is the core of geology. Economic Geology Gallery consist principal exhibits of gold and silver, various types of  ores, refractories, micas, gemstones, building stones, coal, radioactive minerals, lignite, pigments, abrasives and ceramics. A special training course on "Importance of Geological  Specimens" is being conducted to the college students annually from 1996.