Antium

Antium was a chemical element that could be used to build powered armor and other advanced systems. It was quite abundant on the planet Celdaru, but was usually found alongside other metals. It was a lustrous, greenish material, with a high density and melting point and an average atomic weight of 300. First discovered by Galactic Republic scouts in the Expansion Region, it was used for a short time for armor before being succeeded by neutronium alloy.

Its chemical properties were similar to those of other heavy metals, but it was noted for its stability, as its existence was theoretically impossible. Some assumed it was created by the Celestials, but a Republic laboratory studied the material in 22 BBY and found that its protons and neutrons were significantly closer to each other and compressed, which led them to believe that it was formed in hypernovae. This theory was strengthened by the fact that advanced sensors could detect a normally invisible circle producing weak radiation around most planets where antium occured. These were declared to be old hypernova remnants.