Rubidium

In nature, rubidium is found in the Earth's crust, 34 ppm, in minerals such as rhodizite, lepidolite and rubidium carnalite, and in sea water, mineral springs and salt lakes [6]. The isotopes found in nature are ⁸⁵Ru (72.15 %, stable) and ⁸⁷Li (27.85 %, T_½ = 4.8 · 10¹⁰ years) [6].

In pure solid form, rubidium exist in a body-centered cubic crystal structure [6]