Trinium

From SGCommand

Trinium (also called ke) is an element that is a hundred times lighter and stronger than steel. Unrefined trinium is brittle and relatively useless.

The SGC attempted to mine a mountain of trinium on PXY-887, but the local Salish tribe asked them to stop, feeling that their methods were wasteful and destructive. (SG1: "Spirits") However, the SGC was also able to locate another mine.

Trinium is also a component in a compound used in a great deal of Tollan technology. (SG1: "Between Two Fires")

After Earth's Stargate iris was destroyed by a black hole, the Tau'ri installed a new one made of a trinium alloy. (SG1: "A Matter of Time")

Alloyed with naquadah, trinium was an important part in the construction of the Prometheus and Daedalus-class battlecrusiers.