Calcium is a very unusual metal to be formed into density cubes – or anything at all for that matter. In fact, to our knowledge these cubes are the first time pure calcium has been made into a commercial product. 

There are several good reasons for this. Calcium is not stable in air and will oxidize into a powdery mess if left out. In a previous writeup we had penned that the metal is too soft to be useful. That's not entirely correct. It's not particularly soft, it just has poor structural integrity. Apply physical stress to a piece of calcium and it quickly crumbles. That's not softness per se, it's just poor cohesion. In any case, that's definitely not a trait you look for in a metal.

Calcium is much too reactive to be found in nature in its elemental state. To keep it pure it must be stored in mineral oil or, preferably, an inert gas. We are now offering them encased in a glass ampule under argon where it is guaranteed to not degrade as long as the glass doesn’t break.