Dear All,

I  have recently come across the  "Isocon diagram", introduced by James Grant
(1986) as an illustration of Gresen's equation and since used as a standard
diagram  (e.g. Hippert 1996 JSG)  to  illustrate  mass gain or loss in a chosen
rock that may be deformed or metasomatically changed.

It occurs to me that the diagram seems to be overdefined.

In order to plot many elements on the same diagram the element concentrations are
generally  randomly scaled so that the horizontal  axis appears pretty
meaningless. I started thinking that one could normalise all elements to 1 or
something thus freeing the horizontal axis to plot something else (e.g. atomic
radius or something other related to mobility).

Am I thinking in a completely usless direction ? I am a bit nervous as it seems
such a standard diagram...

Pity us mere mortal beings are usually resticted with our imagination to 2D so
that we have to think about things like this at all...


Kurt Stuewe
Institut fuer Geologie und Palaeontologie
Universitaet Graz, Heinrichstr 26.
A-8010 Graz
email: [log in to unmask]
Fax: 0043-316-380-9870
ph:  0043-316-380-5682