Among builders and ordinary people there is a persistent stereotype about the natural radioactivity of granite, the undesirability of its use in the construction of buildings and structures, especially residential ones. The site about natural stone https://kamnemir.ru analyzes this problem in detail. The conclusion is unambiguous: fears about the radioactivity of granite are greatly exaggerated.
Why is granite radioactive?
Granite is formed during the cooling and crystallization of magma. The main potentially radioactive constituent of the rock is quartz (silicon oxide), which includes oxides and salts of radioactive elements, as well as radioactive isotopes of stable elements of the periodic table. Also in the structure of granite are molecules of radioactive gas radon.
The greatest danger to humans and all living things is uranium. Granite is mined at the notorious "uranium mines". The uranium content in the rock is negligible. To obtain raw materials for a nuclear power plant or a bomb, complex and expensive enrichment is required.
Radon is the second most dangerous. It is even less in stone than uranium, but it is a gas, and at the first opportunity it seeps into the air. According to doctors, it is the natural or increased radon background that is the second most frequent cause of malignant neoplasms of the respiratory system after smoking.
Other radioactive isotopes (cerium, lanthanum, other alkaline earth and rare earth metals) are present in granite in negligible amounts and have almost no effect on the radiation background of the rock.
Radiation hazard classification of granites
The content of quartz in granite varies within 35-40%. If it is less, the rock has practically zero radioactivity, if it is more, the stone becomes potentially dangerous. The prospect of a deposit is assessed in a comprehensive manner, by analyzing the physical and technical properties of the stone, its suitability for the construction and construction of roads, the percentage of uranium and the possibility of enrichment. Based on the results of the study, the deposit receives a passport.
According to the degree of safety, natural granites mined in quarries are divided into three classes:
- Class A. A breed approved for use in the construction of residential and public buildings.
- Class B. A stone that can be used for paving roads and erecting road infrastructure within the boundaries of settlements.
- Class C. Species permitted only for use in road construction outside of settlements.
Although Grade III granite is significantly cheaper than Grades A and B, due to the potential risks to people and the environment, it is rarely used, and the deposits are considered unpromising.
Radioactivity of granite in numbers
For Grade A granite, its natural radiation does not exceed 0.05 microsievert per hour. Is it a lot or a little? The normal dose of radiation at sea level for one person is 0.2-0.25 μSv / h.
This includes solar and cosmic radiation (0.035 μSv / h) and incorporated radiation (0.16 μSv / h), that is, exposure to radioactive particles that have entered the body with water, food and air. The remaining insignificant 0.01 - 0.06% is just accounted for by "accidental" doses taken in excess of the background during an X-ray examination or contact with a natural stone.
It is important to avoid purchasing raw materials for construction and renovation from unverified suppliers. A responsible seller of granite tiles, natural stone furniture will certainly show a safety certificate, which indicates the chemical composition of the product or material, its radiation background. If you are particularly suspicious, stock up on a Geiger counter and check the radioactivity of granite or other building or decoration stone when purchasing.
