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. Marine geologists study the ocean flow and investigate ocean basins for mineral and petroleum potential. Engineering geologists use information gathered to advise the relevant authorities on the suitability of sites for the construction of roads, airfields, tunnels, dams and other structures. They decide, for example, whether underground rocks will bear the weight of a building or whether a proposed structure may be in an earthquake-prone locality.