FMS - The Fluorescent Mineral Society

Does anyone have a good-sized piece (ie: fist sized, perhaps) piece of the ever-elusive, California Datolite (yellow fluorescing) for trade or for sale? I've been looking for a piece for what seems like forever. I've seen the white fluorescing calcite from the area (just north of San Francisco), but I haven't seen any decent yellow-fluoresing Datolite whatsoever. Any leads would be much appreciated! Aaron Rever PS: I did find out something interesting about the Lemon Opal from the Napa Valley. I heard that the fluorescence was essentially due to microcrystalline zircon that embedded itself in the opal matrix. I'm not sure how accurate this information is, but I have been told that the yellow fluorescence is most definitely NOT due to hydrocarbon inclusions.