Other long-lived nuclides of potential cosmochemical significance

Other long-lived nuclides of potential cosmochemical significance 

There are several other potential chronometers available. Some preliminary work has been done on some systems, but they are either not widely apphcable or have yet to reach mainstream status. Here we briefly review some of them. 

Platinum-190 decays to 186Os by emission of an a-particle. Both are platinum-group elements and thus the system has potential use for iron meteorites and PGE-bearing mineral deposits. Walker et al. (1997) determined the decay constant of 190Pt (X =(1.542 0.015) x 10 12 yr half-life =4.5 x 1011 years) and established parameters for 

This system has seen only very limited application to natural samples. 

Lanthanum-138 decays to 138Ba by electron capture (66%) and to 138Ce by (3-decay (34%). Lanthanum and cerium are REEs, whereas barium is an alkaline-earth element like calcium and strontium. Both systems have been studied as potential chronometers but are not in 

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