I was having a glass of wine over candlelight and I noticed that the liquid wax was completely transparent but turned opaque when when the wax solidified. Why does this happen? Clearly, when the molecules reorganize during the freezing phase transition they begin to interact with the light. I know this can also happen with water but I not sure it's for the same reason, because the most organized ice is clear. Only when the crystalline structure is disturbed (the ice is fractured, aerated, etc.) does the solid water become opaque. So it seems that the transparent liquid to opaque solid transition in water is due to repeated diffraction and scattering, leading to reflection. Is this the same reason it happens in wax? If so, what molecular changes bring this about?