Here's my partisan view. If it gives a reasonably decent X-ray diffraction pattern, and is a single phase, and is naturally-occurring (not made by humans), and is solid, then it's mineral. Quasicrystals give nice XRD patterns, their rules of repetition are just a bit different than the usual translation + rubber stamp unit cells. Organic crystals are A-OK, too. Liquid crystals are, well, liquid crystals and so not minerals. Amorphous things should be called mineraloids, which means, approximately, interesting-looking things that don't give XRD patterns and so aren't minerals. I'm not a mineralogist, so what do I know? kurt -- Kurt Hollocher Geology Department Union College 807 Union St. Schenectady, NY 12308-3107 USA 518-388-6518 Fax: 518-388-6417 http://minerva.union.edu/hollochk/kth/index.html