Iron concentrations 

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        An attempt was made to correlate different intensities of luminescence on the scanned CL photographic images with trace-element concentrations using the electron microprobe.  Detectable amounts of iron, aluminum, and in some cases, titanium were measured in the vein quartz.  Seven electron microprobe traverses in three samples were performed, measuring the concentration of these trace elements across the darker-luminescing regions of the quartz near sulfide crystals.  The results clearly indicate a higher concentration of iron in the darker-luminescing regions next to the sulfide, with the iron concentration decreasing smoothly away from the sulfide.  The dark-luminescing regions are much wider, ranging up to 140 microns in width, than the expected width of interaction effects of the electron microprobe, which would be less than 10 microns.  Two traverses were repeated using a lower accelerating voltage (10 keV compared to 15 keV for the first traverses) to make sure the iron detected was not due to excitation of iron Ka x-rays in the nearby sulfides by secondary fluorescence.  The weight percent of iron measured in these traverses was close to that measured during the first traverses, indicating that the detected iron was not the result of secondary fluorescence.    Click here to see results   Return to CL Main Page