Rubidium Element Number 37 Rb

Rubidium is an alkali metal, it is very reactive and  can burst into flames in the air. I have less than a gram of Rb in a sealed glass vial. Rubidium is the 23rd most abundant element in the earths crust. The element is very similar to Potassium and Caesium which are in the same group.

Rubidium was discovered by Robert Bunsen and Gustav Kirchhoff, the same Bunsen who created the ever useful Bunsen Burner. Bunsen and Kirchhoff were conducting flame tests and spectroscopy experiments with minerals when they discovered Rubidium.

Like Caesium, Rubidium can be found in the mineral pollucite, and in leucite. and generally extracted as a by product of Caesium extraction. Rubidium has a few interesting applications, photo cells, magnetometers, nuclear medicine, and fireworks. The element is also used in medicine as a positron emitter, and a med for depression. Rb can be used as a "getter" in V tubes.

The Rubidium frequency standard or oscillator is similar to the Caesium "atomic clock". Rubidium 87 is used in a physics package using Rb discharge lamps that  emit light which is passed through resonance cells and photo cells. . The standards are used to time various equipment such as GPS and communications. basically the timing of the atomic frequency.


Pure Rb metal in sealed vial, if it broke it can ignite instantly It looks just like my  Caesium sample, and could be confused.

Rubidium bearing Pollucite gemstone

Ru  37 Alkali metal,  AW:85.4678  MP:102.7  BP:1270  D:1.532  Mohs:.03 

 Exotic Rubidium compound, Rubidium Carbonate.

 Strontium Element Number 38 Sr

Pure Strontium metal with its typical texture. I split the piece one minute before photo to try to capture its appearance. 

 Sr 38 Alkaline earth metal,  AW:87.62  MP:1431  BP:2526  D:2.64  Mohs:1.5

Strontium metal is the 15th most abundant element, and is found in the mineral celestite. Strontium is a reactive metal in the group with Calcium. Like Calcium, Strontium will produce Hydrogen gas when exposed to water. Strontium will also spontaneously ignite when in powder or finely divided form.

Strontium has 3 allotropes and these have temperature transition points, meaning they change at different temperatures to different variety of the element. Strontium has 4 natural isotopes and 16 unstable isotopes.

 Two isotopes of note are Sr89, which is used in nuclear medicines to treat bone cancer. Also Sr90 is a by product of U235 and Pu239 fission either from a reactor or weapon, has a half-life of  28.78 years. The isotope Sr90 can be absorbed by bones as Calcium can, and cause serious health issues because it is a radioactive high energy beta emitter. You just don't want to have radioactive bones, its not cool. Sr90 may have uses in power sources, and also some medical treatments.

Strontium can be used in fireworks, flares, CRT TV screens, as an X ray absorber.  In tooth paste for sensitive teeth  like mine, also magnets, Aluminum alloys, and medicines.

I have quite a pile of this metal, and as small samples go, I have some fair prices.