Radiometrics

Uranium, thorium, and potassium occur naturally in earth materials, and being radioactive, anomalous concentration may be detected by radiometric surveys. Only gamma radiation is useful in exploration, because alpha and beta emissions are masked by a thin cover of soil, water, or air. Gamma ray emissions penetrate only a few inches of soil or a few hundred feet of air, so that the radioactive ore deposit must virtually outcrop at the surface to be detected.

Geiger counters and scintillometers are easily portable and can be held in the hand, mounted in surface vehicles, or operated from aircraft. Airborne radiometric surveys were successful during the 1950's in exploration for uranium in Colorado, Utah, Arizona, and New Mexico.