The crystal structure of garnet is much simpler than that of silica which has about 10 crystal forms! Anyone interested in silica is welcome to peruse this link: Silicon dioxide - Wikipedia, the free encyclopedia, it is very interesting, BTW there is a meta-stable orthorhombic form as well! As if I wasn't already craxy enough! It turns out that the dodecahedron structure is a lowest energy geometrical structure that even things like lather and all types of foams like to assume. Not that it matters but having made a living studying polyurethanes this has always fascinated me. And Howard, here is my public permision to use the pics of my big B/G Escher and my Y/G Escher that you can find in this sub-forum for your museum. Thanks for all your work and help to this community! BTW, we all have an idea as to the abrasive content in Belgian stones, about 30-45% garnet but do you or anyone know the abrasive content, that is, the range of silica % in Eschers? And if I might be so bold as to ask, does anyone know the aproximate % of silica of the major Escher classifications, i.e. Dark Blue, Blue Green and Yellow Green? OK, know everyone can say that I'm truly crazy!