How accurate is potassium argon dating

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This mineral sample is then baked gently overnight in a vacuum furnace.

These steps help remove as much atmospheric Next, ​the mineral sample is heated to melting in a vacuum furnace, driving out all the gas.

That is, a fresh mineral grain has its K-Ar "clock" set at zero.

The rock sample to be dated must be chosen very carefully.

The calcium-potassium age method is seldom used, however, because of the great abundance of nonradiogenic calcium in minerals or rocks, which masks the presence of radiogenic calcium.

But micas, plagioclase, hornblende, clays, and other minerals can yield good data, as can whole-rock analyses.

Young rocks have low levels of The rock samples are crushed, in clean equipment, to a size that preserves whole grains of the mineral to be dated, then sieved to help concentrate these grains of the target mineral.

The key is to put the mineral sample in a neutron beam, which converts potassium-39 into argon-39.

Because Ar has a very short half-life, it is guaranteed to be absent in the sample beforehand, so it's a clear indicator of the potassium content.

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