Alkaline Earth - Occurrence

Occurrence

Beryllium occurs in the earth's crust at a concentration of two to six parts per million (ppm), much of which is in soils, where it has a concentration of six ppm. Beryllium is one of the rarest elements in seawater, even rarer than elements such as scandium, with a concentration of 0.2 parts per trillion. However, in freshwater, beryllium is somewhat more common, with a concentration of 0.1 parts per billion.

Magnesium and calcium are both incredibly abundant in the earth's crust, with calcium being the fifth most abundant element, and magnesium the eighth. While none of the alkaline earth metals are ever found in their elemental state, magnesium and calcium are found in many rocks and minerals. Magnesium is often found in carnellite, magnesite, and dolomite, while calcium is often found in chalk, limestone, gypsum, and anhydrite.

Strontium is also incredibly common on earth, being the fifteenth most abundant element in the crust. Most strontium in the crust is in the minerals celestite and strontianite. Barium is slightly less common, and much of it is in the mineral barite.

Radium, being a decay product of uranium, is found in all uranium-bearing ores. Due to its relatively short half-life, no radium that was present when the earth was formed is still around today, and instead has all come from the gradual decay of the uranium.