3.5 out of 5

http://www.unitednuclear.com/supplies.htm

Ever few years I stumble back onto United Nuclear.  If for nothing else, it’s a great site to wander around on and dream about owning your own piece of rubidium.

Rubidium is one of the most reactive metals known to man – it will ignite upon exposure to air or water. For protection, our Rubidium samples are sealed in glass ampoules under Argon gas.