Titanium

Titanium (pronounced /taɪˈteɪniəm/) is a chemical element with the symbol Ti and atomic number 22. It is a light, strong, lustrous, corrosion-resistant (including to sea water and chlorine) transition metal with a grayish color. Titanium can be alloyed with iron, aluminum, vanadium, molybdenum, among other elements, to produce strong lightweight alloys for aerospace (jet engines, missiles, and spacecraft), military, industrial process (chemicals and petro-chemicals, desalination plants, pulp and paper), automotive, agri-food, medical (prostheses, orthopaedic implants, dental implants), sporting goods, jewelry, and other applications. Titanium was discovered in England by William Gregor in 1791 and named by Martin Heinrich Klaproth for the Titans of Greek mythology.

In the Halo Universe
Titanium is a major component in the UNSC's Titanium-A armor, and is also used in the construction of the Warthog FAV and its variants. The planet Reach had plentiful deposits of titanium, which were the original reason for its colonization. With numerous titanium mines, Reach was the largest non-automated exporter of titanium in UNSC-controlled space by 2535.