A professional who tests sand, shale, and other earth materials to determine petroleum and mineral content and physical characteristics. Responsibilities include:

• Performs routine chemical or physical tests of earth samples in field or laboratory to determine content of hydrocarbon or other minerals indicating presence of petroleum and mineral deposits.
• Tests core samples brought up during well drilling to determine permeability and porosity of sample, fluid content of sand and shale, salinity of drilling mud, and other conditions affecting oil well drilling operations.