A lot of labrotory geology has (or had - methods may have changed drastically in the last few years) to do with looking at rocks glued to slides and ground to a specific thickness so that they can be viewed in microscopes specially designed to work with indices of refraction - did a lot of this type of thing in my school daze. snd so was one of the first things I picked up on in Bryce. Unfortionallybecause of my background I keep trying to approach art from a scientific point of view it seldom works - but this may - with translucent or transparent objects. - TJ