Naturally occurring radioactive material

Naturally occurring radioactive materials (NORM) and technologically enhanced naturally occurring radioactive materials (TENORM) consist of materials, usually industrial wastes or by-products enriched with radioactive elements found in the environment, such as uranium, thorium and potassium-40 (a long-lived beta emitter that is part of natural potassium on earth) and any of the products of the decay chains of the former two, such as radium and radon. Produced water discharges and spills are a good example of entering NORMs into the surrounding environment.

Source: Wikipedia — Naturally occurring radioactive material (CC BY-SA 4.0)