Some rare stuff: metallic rubidium(: 

Did you know that rubidium is slightly radioactive with a half-life of 49 billion years, what is more than three times longer than the estimated age of the universe.

And also an interesting fact that rubidium is much more rare than cesium what is under rubidium on the periodic table.

9:22 pm  •  19 July 2012  •  20 notes