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.

What is potassium-40 used for?

The very slow decay of potassium 40 into argon are highly useful for dating rocks, such as lava, whose age is between a million and a billion years. The decay of potassium into argon produces a gaseous atom which is trapped at the time of the crystallization of lava.

Can potassium-40 be used in radiometric dating?

The potassium-argon method can be used on rocks as young as a few thousand years as well as on the oldest rocks known .RADIOMETRIC TIME SCALE.Parent IsotopeStable Daughter ProductCurrently Accepted Half-Life ValuesRubidium-87Strontium-8748.8 billion yearsPotassium-40Argon-401.25 billion years4 more rows•13 Jun 2001

Is potassium-40 used to date fossils?

The half-life of potassium-40 is 1.3 billion years. Rocks can require 200,000 years for enough argon gas to build up to provide an accurate measurement. As a result, this technique is used to date older objects. There is effectively no upper age limit for this kind of dating.

Is potassium-40 Harmful?

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.

How far back can potassium argon dating go?

Potassium-argon dating is accurate from 4.3 billion years (the age of the Earth) to about 100,000 years before the present.