The phrase "element strontium" refers to a type of substance that exists naturally, which is called strontium. It is one of the many different substances known as elements, which are the building blocks of everything in the universe. Full definition
Animals pick up the chemical element strontium through their diet, and it leaves a record in their teeth. (sciencenews.org)
Studying the spectra of the stars, the researchers found unexpectedly high abundances of the heavy elements strontium (Sr) and yttrium (Y). (sciencemag.org)
However, corals sometimes substitute the element strontium for the calcium. (sciencedaily.com)