WHAT IS GAMMA RADIATION?
Everything around us emits natural gamma radiation. Gamma rays are emitted through the decay of radioactive elements. These rays are invisible, high energy rays that are capable of penetrating most other materials. Uranium, Thorium and Potassium are examples of common radioactive elements found in and on the earth. Shale and clay minerals contain larger than normal amounts of radioactive materials. Sand, sandstone, quartz and lime or limestone contain much less radioactive material.
Gamma ray logging is used in definition of coal seams, it is important to note that coal contains very low amounts of radioactive material.
GAMMA RAY LOGGING:
Gamma ray logging tools are available for the purpose of logging natural gamma radiation. The tools contain a sensitive scintillation detector and electronics that send pulses representing detected gamma rays to the surface. A gamma ray log will show where sandstone, clay, shale and other layers are. It will show thickness of each of these zones.