Question #2ca99

1 Answer
Mar 3, 2017

Answer:

The glass slowly crystallizes as it ages.

Explanation:

Most glass is an amorphous form of silicon dioxide, #"SiO"_2#.

In contrast, the atoms in quartz, the crystalline form of #"SiO"_2#, are in a highly ordered arrangement.

quartz/glass
(From Reddit)

As time passes, the glass is subjected to many temperature changes, such as from day to night.

Over a long period, small areas within the glass will crystallize.

These crystalline areas scatter the light in different directions, causing the glass to appear milky.