So I admittedly was a former cocaine user. I've since cleaned up and am back in school and my life is going in the right direction for once. I took a class in organic chemistry this previous semester and we did a lab on recrystallization. I think it was boric acid that I recrystallized, but I remember reading before that transparent crystals tend to be the purest. Anyway, one thing about cocaine is that when it is of very high quality (high purity), it is composed of pearly flakes which are not transparent at all. They look silverish, like aluminum. Very shiny. Why is it that cocaine crystals, when they're of high purity, aren't transparent but other crystals are? This seems counter-intuitive to me.