CompuServe Messages

Here's one for you fluorescent-mineral hounds: I have a sample of rock from an oil-well core cut in the Jurassic Nordegg Member of the Fernie Formation in Alberta, Canada. The main lithology of the Nordegg member is dark brown to black, calcareous, very organic/petroliferous marine shale. The shale is locally phosphatic (biogenic phosphate–fish bones, pellets, etc.). Without trying to open another can of worms vis-a-vis origin of petroleum, I'll baldly state that the Nordegg is an oil source-rock. The fluorescent mineral in question occurs in occasional thin (to 1") layers within the main Nordegg shale. Here are the basic visual properties: Color: medium greenish grey, slightly translucent in thin flakes Lustre: dull to slightly waxy Habit: compact (cryptocrystalline at 30x magnification), extremely fissile (flaky) Fluorescence: brilliant yellowish white (3600A: standard UV light for oilfield use…I don't have a shortwave light, so can't help you there.) Under the microscope, this mineral has tiny flakes of biotite scattered throughout. Also, the Nordegg is very radioactive on standard gamma-ray logs. Some of the "mystery mineral" layers seemed to correlate with spikes of gamma radiation, but this is inconclusive, due to the relatively low resolution of the log (approx. +/- 0.5 metre). I don't have access to a geiger-counter, so can't test the samples directly. My feeling is that these layers resemble altered volcanic ash beds, which are relatively common in the Western Canada basin, and are usually bentonitic in composition. However, I have never run across any that showed such intense fluorescence (or any fluorescence at all, for that matter…) Have any of you seen any clay minerals with brilliant yellowish white fluorescence like this? Any other ideas? Thanks, Howard