Iridium

"Iridium is made from layers of Iridium and other metals. It performs better than Tritanium."

General
Iridium is a direct upgrade over Tritanium, commonly used in medium-level fleets.

Advantages
Iridium is fairly mass-efficient and offers good protection, suitable for Tier 2-3 ships such as Exodus Cruisers and Nighthawk Frigates.

Disadvantages
Iridium is still inferior to Zynthium, the best researchable armor in the game.

XP also starts to become a major problem: if you wish to limit your fleet level, consider using lower-tier armor even though they may be less mass efficient.

Trivia

 * It used to be called Iridium Composite along with the base version, but was simplified to Iridium.
 * The same material that make up this armor is used for Iridium Magnets and Iridium Arrays as a weapon booster.
 * Iridium is a real metal, favored for its high density, corrosion resistance and melting point. It is one of the two elements of the alloy used for the International Prototype Metre Bars. It is also one of the rarest stable metals in the Earth's crust.