CompuServe Messages

Hi, Norm– I'd love to get a sample of this rhyolite with fluorescent silica phenocrysts. Can you be more specific about where one obtains some? I am also curious as to which silica mineral it is – quartz? Blue is mildly surprising as a daylight color caused by radiation damage; I expect black (or brown) smoky quartz normally, or with some ferric iron present, the purple of amethyst. The radiation may be reacting with some other impurity in the quartz to get a blue result, perhaps an unusual impurity like some rare earth element. –Doug