Cesium in Our Time

The rubidium isotope Rb is radioactive and makes up 27.8% of all natural rubidium. Because of that it is used in the rubidium/strontium technique for dating rocks. 

Some rubidium compounds are used in more ordinary applications. Rubidium carbonate is added to the melt during the manufacture of certain special glasses. Rubidium bromide is used as a luminescent material in viewing screens. Rubidium is also used in the manufacture of photocells and as a scavenger in vacuum tubes to remove traces of gases. 

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