Date: Fri, 23 Dec 94 12:08:33 NST
Subject: Re: SX-50 spectrometers. oscillations at rest
From: maggy@microprobe.esd.mun.ca (Maggy Piranian)

Subject: mica orientation



Several years ago I analyzed phlogopite, some of which I had mounted

vertically and some horizontally. I found a very significant difference

in Mg and Fe analyses between the two orientations. To my surprise, when

a few days ago I checked composition as a function of orientation of

biotites in a thin section, I found no difference. Does anyone know

about this ? Is it a difference between phlogopite and biotite ?

Synthetic (phlogopite) and natural ? The way samples were polished ?

With the phlogopite, it was the vertical grains that gave analyses

closest to the wet chemistry. What causes the different anayses

in the phlogopite ?

Maggy Piranian

Earth Sciences

Memorial University of Newfoundland