An important application of the geologist's labour is locating oil, natural gas, minerals, metals, coal and underground water. Geologists also examine chemical and physical properties of specimens in laboratories, under controlled temperature and pressure. They usually study fossil remains of both animal and plant life or experiment with the flow of water and oil through rocks. Laboratory equipment used by geologits include complex instruments, such as x-ray diffractometer, which determines the crystal structure of minerals, and the petrographic microscope used for close scrutiny and study of rock formations and sediment samples. Beside locating resources and working in laboratories, geologists, also advise construction companies and governmental agencies on the suitability of certain locations for constructing buildings, dams or highways.
Some geologists administer and manage research and exploration programmes.
Others teach and work on research projects in universities. Geologists generally work in a variety of specialty areas such as earth minerals, earth processes and earth history. Economic geologists locate minerals and solid fuels. Petroleum geologists attempt to locate underground oil and natural gas deposits. Some petroleum geologists work on specific drilling projects, while others develop petroleum related geologic information for entire regions.