Calcium is one of the most common elements on earth. Calcium carbonates and sulphates simultaneously create magnificent stalactite caves, beautiful minerals, filigree mussel shells and of course our bones. And the slightest changes in the concentration of calcium ions are the basis for all of our senses.

To the article about calcium on the Fascination Chemistry website

Calcium belongs to the 2nd main group of the periodic table, the group of alkaline earth elements.