Hi
Silver!
Here's a list with figures from the Nordic Mythology, and you'll find "Mist" on it as well:
http://www.geocities.com/Area51/Shadowlands/4826/asagudinnor.html
I'm sorry about Valhall. It's the Swedish form of the word. I just had a look in my dictionary, and there the English form is written as "Valhall(a)", so I think in English both versions are possible!
Regards,
Satu