Short answers, pulled from the story.
Humphry Davy isolated the metal itself on the 2nd of May 1807 through electrolysis of molten caustic potash. This event marked the first time a metal was ever isolated by this method. Davy's discovery proved that potassium and sodium were distinct elements.
A 60-kilogram adult contains approximately 120 grams of potassium. This amount makes it the eighth or ninth most common element by mass in the human body. The element resides inside individual cells to maintain the electrical potential necessary for nerve transmission.
Canada leads the world in potash production with the easiest deposits lying 1,000 meters below the surface of the province of Saskatchewan. Other major producers include Russia, Belarus, and Kazakhstan. Israel and Jordan utilize the concentrated potash in the Dead Sea.
Potassium-40 has a half-life of 1.25 billion years and decays into stable argon-40. This decay allows scientists to date minerals such as biotite, muscovite, and volcanic feldspar. The method is particularly effective for dating volcanic flows and shallow intrusives that have remained unaltered.
When potassium compounds are introduced to a flame they emit a distinctive lilac color with a peak emission wavelength of 766.5 nanometers. This flame test is so characteristic that it remains a primary method for detecting potassium in qualitative analysis. The property has been used for centuries to identify the element in the laboratory.