Type of Radiation Emitted From Granite

The natural beauty and rugged durability of granite have made it a favorite material for some aspects of home decorating. One particular application is in the making of high-end kitchen counter tops. However, like any natural rock formation, granite contains traces of radioactive elements. These can result in some radiation being emitted from granite fixtures in the home, although the Environmental Protection Agency has stated that the amount of radiation from granite in the home is likely not dangerous.

Radioactivity

• Granite is a mineral that is produced through a slow process from the crystallization of molten rock. It contains a wide variety of elements and minerals, some of which are radioactive. A radioactive element is one in which the molecules periodically break down, releasing either particle or electromagnetic radiation. If this radiation has enough energy to detach electrons from atoms, it is said to be ionizing radiation and can be dangerous. Naturally occurring radioactive elements in granite include thorium and uranium.

Alpha and Beta Radiation

• Two types of particle radiation that can potentially be emitted by elements found in granite are alpha and beta radiation. Alpha radiation is made of particles composed of two neutrons and two protons. Although it is ionizing radiation, it has little penetrating power and can be stopped by a sheet of paper. However, it can damage living tissue if the elements emitting this radiation are inhaled or ingested. Beta radiation is made of fast-moving electrons. Beta is more penetrating than alpha, but it will still be stopped by a sheet of aluminum foil.

Gamma Radiation

• Another form of ionizing radiation that can result from elements in granite is gamma radiation. This can be released from radioactive isotopes of protactinium, lead and other species. Gamma radiation is emitted as electromagnetic radiation rather than particles, in a form similar to x-rays. It has much more penetrating power than either alpha or beta particles and can easily penetrate clothing and other barriers to cause damage to the interior of the body.

Radon

• Radon is a colorless, odorless gas. It is formed from the natural decay of radioactive elements such as uranium. The radioactive decay of radon produces alpha radiation of the same kind produced by other radioisotopes. Since radon can be inhaled, it can be damaging to lung tissue. Isotopes in granite can produce and release radon gas inside the house. The Environmental Protection Agency, however, estimates that the release of radon from granite in the home is likely minor in comparison to the radon that enters a house from the soil it sits on.