At 05:03 PM 1999/04/27 +0800, R Liu wrote:
>Dear sirs,
>A mineral which is extremely rich in Potassium is found in two rocks from
greenshcist belt.It looks like mica under thin section. The coexisting
minerals are actinolite, epidote, muscovite , albite and qtz. Some EPMA
analysis results are shown as following: ...
Assuming the analyses are accurate and the 'missing' ~6 wt% is H2O, it looks
like a new mineral, roughly K4Al3Si6O16(OH)5.
Intriguing that this peralkaline mineral evidently coexists with a
peraluminous mineral (muscovite) plus quartz. Accordingly, there would be a
reaction relationship with Kfeldspar plus H2O:
2 K4Al3Si6O16(OH)5 + KAl2AlSi3O10(OH)2 + 12 SiO2 = 9 KAlSi3O8 + 6 H2O
Is the "greenschist belt" abnormally high P/T ?
Dugald
Dugald M Carmichael Phone/V-mail: 613-533-6182
Dept of Geological Sciences and Geological Engineering
Queen's University FAX: 613-533-6592
Kingston ON K7L3N6 E-mail: [log in to unmask]
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