mirror of 1/4" thick, and i have been trying to do this, but installers are always telling me not to use mirror bigger then 12' x 12' because of the weight and told me it could be an hazzard... but 12'' x 12'' has not the same effect.
door is 3 1/2" thick and solid, so it required a beefy jamb, which is welded heavy steel square tubing. The raw steel jamb is wrapped with clear anodized aluminum break metal for a clean "storefront" look.