Sorry, all - hit send too soon. Typing with an infant in your lap is probably unwise.
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Dave Hirsch
Associate Professor
Department of Geology
Western Washington University
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On Sunday, January 27, 2008, at 06:57AM, "Eric J Essene 1" <[log in to unmask]> wrote:
>Dr Hajialioghli,
> A simple assumption is that all Ti is 4+ and on the VI site.
>Using an 8 cation normalization you can fill the IV site with Al and
>then Fe3+ if needed, and then calculate a Fe3+/Fe2+ by driving O =
>12. Fe2+ can be on either the VIII or the IV site in melanite.
> This approach is obviously a model, but it is the kind of
>calculation used for hornblende and clinopyroxene by many petrologists.
>eric
>
>
>On Jan 27, 2008, at 3:11 AM, r h wrote:
>
>> Dear list members,
>>
>>
>> I am recently working on some high Ti-bearing garnets (mainly
>> melanite) in alkaline rocks. I have a problem in allocating cations
>> to appropriate crystallographical sites. I have microprobe analyses
>> of major oxides in the garnet, but there is no information on Ti
>> and Fe valance state in these minerals. Are you aware of a
>> practical method (or software) for calculating formula of such
>> unusual garnets? Any idea how R-mode for factor matrix can be
>> calculated (Table 3 of paper by Dingwell and Brearley, Cont.
>> Min.Pet.,1985, 90: 29-35).
>>
>> Sincerely
>>
>>
>> R. Hajialioghli
>>
>> Support the World Aids Awareness campaign this month with Yahoo!
>> for Good
>
>
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