Beryllium is an extremely hard metal in the alkali metal group. It is fairly stable as of the alkaline earth metals since it has a good grip on its electrons. The hardness on the Mohs scale is 5.5, and the metal is brittle and unyielding. This can help, though, as in outer space, there is no oxygen(earth) and there is no atmospheric pressure. So the metal will not break but can serve as a frame for spacecraft.
Beryllium was first discovered in beryl, a mineral also related to emeralds. This places up to 8 on the Mohs scale, and as in emeralds, there are hints of chromium. Louis Nicolas Vauquelin was investigating the difference between beryl and emerald, and so discovered beryl.
Sources Of Berylium
There are many naturally occuring varieties of Beryl. Beryl(a naturally occuring Berylium containing ore) is an important source of natural Berylium metal for industry and commercial reasons.