Open Adit™ - Mineral Properties / Radioactivity

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Radioactivity is the spontaneous decay or disintegration of an unstable atomic nucleus of an atom of one element to produce one or more new nuclides and the emission of radiation (energy). The radioactive isotopes of potassium, strontium, thorium, uranium and samarium (⁴⁰K, ⁸⁷Sr, ²³²Th, ²³⁸U, ²³⁵U, ²⁴⁷Sm) are geologically important for absolute age dating and as a diagnostic tool. The radioactivity of some uranium- and thorium-rich minerals is great enough that it can be detected by a Geiger counter and is therefore a diagnostic property. The radioactivity of these and other radioactive minerals may also pose a health risk.

There are three mechanisms of radioactive decay: alpha decay, beta decay and electron capture. Alpha decay results in the emission of an alpha particle. The alpha particle (a) is identical to the nucleus of ⁴He (helium) atom and consists of two protons and two neutrons. The decay of uranium -238 is an example of alpha decay. Alpha decay reduces the mass number of the nucleus by four and the atomic number by two due to the loss of two protons and two neutrons from the parent isotope.

²³⁸U => ²³⁴Th + a + g + Energy

Beta decay results in the emission of a beta particle (b). A beta particle is equivalent to a negatively charged electron. The beta particle is formed through the decay of a neutral neutron particle into a positively charged proton.

⁸⁷Rb => ⁸⁷Sr + b^- + Energy

Electron capture occurs when an orbital electron is captured by the nucleus. The decay of potassium -40 to argon -4o occurs through electron capture. The nuclear charge decreases by one without any significant change in mass.

⁴⁰K + orbital e^- => ⁴⁰A + g + Energy

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