trace element

This term is used primarily in biological, medical, and nutritional contexts to describe minerals that are essential for life but needed in minute amounts. It carries a technical, scientific register and is typically found in textbooks, health reports, or dietary guidelines.

While "trace" implies a very small quantity, the term does not suggest that the element is optional or insignificant. On the contrary, a deficiency in a trace element can lead to severe physiological dysfunction, making the term a paradox of small quantity but high importance.