[R] R, geochemistry, ternary diagrams

[Richard A. O'Keefe]

I'm in e-mail contact with a geochemist who maintains a well regarded
geochemistry web site.  He's drawing diagrams either with a Turbo Pascal
program running in a DOS window or with Excel.  I'm trying to persuade
him that R would be a better choice.  Something he's particularly keen
on is ternary diagrams.  I think he is talking about ternary phase
diagrams, and if so, it looks as though it should be doable in R, but
I don't know enough about the lower levels of R graphics to do it myself
(yet).  Looking at his speed and volume requirements, R can handle them
easily, even on a machine about 1/4 of the speed he has in mind.

Are there enough geochemists using R already that he'd find like-minded
people to discuss technical issues with if he _did_ switch to R?
Is there a package somewhere already that does ternary and other
geochemistry diagrams?