CompuServe Messages

Hi, Howard– >> Most of the kaolinite I run into doesn't fluoresce at all, at least not in long-wave. For typical fluorescences it is very sensitive to locale and impurities. Calcite may fluoresce more or less any color, and most often does not fluoresce at all. There may be one particular site that offers fluorescent kaolinite, or perhaps more likely there was something associated with the "fluorescent" kaolinite. >> As well, the fluorescence was noticeably reduced. Holding the chips in an open flame (alcohol) for a few seconds causes them to turn darker grey (I don't think due to soot), and fluorescence is lost completely. While loss of fluorescence may be due to chemical changes in the suspected hydrocarbons, there are other cases of fluorescence disappearing on heating as crystal defects are healed or things of that sort. For example, chlorophane fluorite fluoresces bright blue-green, unless you leave it out in the sun a short while, which is enough to reduce it to a feeble version of the blue-violet fluorescence more often found in fluorite. >> Perhaps the smectites preferentially adsorb lighter fraction (condensate/gasoline range) hydrocarbons. Or, perhaps being structurally integrated into the montmorillonite layers somehow enhances the fluorescence. While I prefer selective adsorption as an explanation (zeolites and clay minerals are used as catalysts for such reasons), I could live with the other as well. If the montmorillonite scatters UV around so more surface of hydrocarbons is illuminated, a fluorescence might be brightened. I wonder how transparent these minerals are to UV… I'll be moving too soon to rely on snail-mail and do not know what my future snail-address will be; if you do not have the case closed in a couple of weeks I will send my new address. –Doug