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

How old can potassium-argon dating work?

The potassium-argon dating method has been used to measure a wide variety of ages. The potassium-argon age of some meteorites is as old as 4,500,000,000 years, and volcanic rocks as young as 20,000 years old have been measured by this method.

What will happen to a rock that contain potassium in argon after 1.3 billion years?

It has a half-life of 1.3 billion years, meaning that over a period of 1.3 Ga one-half of the 40K atoms in a mineral or rock will decay to 40Ar, and over the next 1.3 Ga one-half of the remaining atoms will decay, and so forth (Figure 19.18). Potassium feldspar does not contain any argon when it forms.

Is potassium-argon dating accurate?

Potassium-argon dating is accurate from 4.3 billion years (the age of the Earth) to about 100,000 years before the present. Eventually, potassium-argon dating may be able to provide dates as recent as 20,000 years before present.

How did they determine the age of the Earth?

By dating the rocks in Earths ever-changing crust, as well as the rocks in Earths neighbors, such as the moon and visiting meteorites, scientists have calculated that Earth is 4.54 billion years old, with an error range of 50 million years.

How old is a rock that in which 65% of the potassium-40 has turned into argon-40?

1.25 billion years In your case, you know that potassium-40 has a half-life of 1.25 billion years because thats how long it takes for half of the number of atoms present in the sample to decay to argon-40.

Is argon-40 Stable?

Argon (Ar) has three natural isotopes with masses 36, 38, and 40. Ar and 38Ar are stable, that is, they are not radioactive, and they are also not produced by radioactivity processes.