Caesium (Cs #55) is the next element on the periodic table for my APEX mineral collection.
Caesium starts row 5 (Period 4) on the periodic table.
Caesium Minerals - The are very few Caesium minerals and they are all salts.
Pollucite ((Cs,Na)2Al2Si4O12•(H2O)) with 28% Caesium is the only practical choice for my APEX mineral. It is only found at Bernic Lake, Manitoba, Canada.
Caesium is a liquid at or near room temperature. It is one of the most reactive elements and is highly explosive when it comes in contact with water. Caesium is the least electronegative element (does NOT attract electrons from other elements).
Caesium was unknown until modern times.
Caesium is not known to be necessary for any living organisms. However, Caesium s easily substituted for Potassium in biologic functions.