Wiktionary
native element
n. (context chemistry geology English) any chemical element which occurs in nature uncombined with other elements; includes the atmospheric gases, several metals and semimetals, and the nonmetals sulfur and carbon
Usage examples of "native element".
There would be no bathing for them this day, but, like a sea-god, Harry Lehr was costumed for his native element.
Soon the Nautilus returned to her native element, and the manometer showed that she was about thirty feet deep.
The light was equal in all directions, only his ascending bubbles indicated the direction of his native element.
A moment later she separated from her shadow and began climbing smoothly over the Sherrington Works on the way to the ultimate freedom of her native element: deep interstellar space.