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. Thus, the ratio of argon-40 and potassium-40 and radiogenic calcium-40 to potassium-40 in a mineral or rock is a measure of the age of the sample.

When using potassium-argon dating to find the age of a rock are the ages we get an overestimate or underestimate of the true age?

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.

What happens in potassium-argon dating?

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 argon dating method?

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 U 238 used for?

Depleted uranium (uranium containing mostly U-238) can be used for radiation shielding or as projectiles in armor-piercing weapons. Where does it come from? U-235 and U-238 occur naturally in nearly all rock, soil, and water. U-238 is the most abundant form in the environment.