Parenthesis/Insertion after "or"

Question

Is it valid in English to use a construction like:

Fog consists of tiny water droplets or, rarely, ice crystals.

If not, how can I elegantly solve this problem?

Answer 1

I think it's ok how you said it, but you can make it a little easier to read by stating something like this instead:

Fog consists of tiny water droplets and occasionally ice crystals.

or

Fog consists of tiny water droplets with the rare formation of ice crystals.