Potassium-argon dating (or K-Ar dating), Rubidium-strontium dating (Rb-Sr), Uranium-lead dating, various kinds of Uranium disequilibrium dating, Fission track dating, and Carbon-14 dating are the most common methods. There are also about 50 other kinds of radiometric dating, most of which are experimental, or of limited application, or give unexpected results for naturalistic assumptions about the age of life on earth. Amino acid dating is sometimes included in discussions of radiometric dating, even though it does not rely on radioactivity for its measurement of age. Dating by Pleochroic haloes is surrounded by controversy.

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