Potassium-argon dating, method of determining the time of origin of rocks by measuring the ratio of radioactive argon to radioactive potassium in the rock. This dating method is based upon the decay of radioactive potassium-40 to radioactive argon-40 in minerals and rocks; potassium-40 also decays to calcium-40.

Is potassium-argon dating reliable?

Potassium-argon dating is accurate from 4.3 billion years (the age of the Earth) to about 100,000 years before the present. At 100,000 years, only 0.0053% of the potassium-40 in a rock would have decayed to argon-40, pushing the limits of present detection devices.

How does potassium decay into argon?

When an atom of potassium 40 decays into argon 40, the argon atom produced is trapped by the crystalline structure of the lava. It can only escape when the rock is in its molten state, and so the amount of fossilized argon present in lava allows scientists to date the age of the solidification.

Is potassium-argon a relative dating technique?

Relative or archeological interest to. Luckily, potassium-argon dating methods is common forms of radioactive potassium-40. Is an absolute age determination used dating, and minerals, and relative dating k–ar dating methods are, is. Potassium-40 to determine relative dating methods can say exactly how old.

What is the ½ life of potassium-argon dating?

about 1,300 million years The Potassium-Argon dating method is the measurement of the accumulation of Argon in a mineral. It is based on the occurrence of a small fixed amount of the radioisotope 40K in natural potassium that decays to the stable Argon isotope 40Ar with a half-life of about 1,300 million years.

Is potassium-40 harmful to humans?

hazard. The strong gamma radiation associated with the electron-capture decay process (which occurs 11% of the time) makes external exposure to this isotope a concern. While in the body, potassium-40 poses a health hazard from both the beta particles and gamma rays.