It is this sorting ability which distinguishes the spectrometer from instruments which measure only total radioactivity. Potassium, uranium and thorium are the three most abundant, naturally occurring radioactive elements. K is a major constituent of most rocks and is the predominant alteration element in most mineral deposits. Uranium and thorium are present in trace amounts, as mobile and immobile elements, respectively. As the concentration of these different radioelements varies between different rock types, we can use the information provided by a gamma ray spectrometer to map the rocks.
Airborne methods provide valuable, systematic coverage of large areas.
Ground spectrometry greatly improves the resolution of individual radioelement sources. By relating radioelement variations measured by a properly calibrated ground spectrometer to relevant lithogeochemical variations, based on a control group of samples, you can substantially reduce your analytical costs. Ground surveys do not require a corresponding airborne survey. They are easily conducted by one person as a reconnaissance survey or using grid lines. The resulting geochemical information provides an important additional layer of information significantly improving bedrock and surficial mapping and ore-vectoring.