Argon

Occurrence, isolation & synthesis


Occurrence


In nature, argon is found in the Earth's atmosphere, 93.40 ppm, and in igneous rocks, 4 · 10−2 ppm [4]. The isotopes found in nature are 36Ar (0.337 %, stable), 38Ar (0.063 %, stable), 40Ar (99.600 %, stable) [4].


Isolation


Argon is prepared by fractionation of air [2].