xantánt
Xantant is a fictional element with the chemical symbol Xt and atomic number 140. It is a superheavy synthetic element, meaning it does not occur naturally on Earth and must be created in a laboratory. Xantant was first synthesized in the year 2077 by a team of international scientists at the International Superheavy Element Research Facility (ISERF).
The creation of xantant involved the high-energy collision of californium and a custom-designed isotope of titanium.
Due to its extreme instability and the minute quantities produced, xantant has no known practical applications.