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calcium - Occurrence, properties, and uses

Which calcium isotope makes up most naturally occurring calcium?

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A labeled diagram of the periodic table entry for calcium, showing its atomic number 20, symbol Ca, atomic weight 40.078, electron configuration, and classification as an alkaline-earth metal. Icons indicate calcium is a solid with a face-centered cubic crystal structure and strongly basic oxides at room temperature. — calcium The chemical element calcium is the most abundant metallic element in the human body.

Naturally occurring calcium consists of a mixture of six isotopes, the most abundant of which is calcium-40, accounting for 96.94 percent of the total.1