Two pieces of quartz people have given to me at different times have become gradually clear over the space of a few years. Previously they were very cloudy, translucent without any detail visible through them. Under a 10x hand lens they appeared to have numerous tiny inclusions or fracture scattered throughout. Now I am able to hold the specimens on a book and clearly read text through them.
What was the nature of the visual obstructions and what is the mechanism by which the obstructions disappeared?