A unique compound which can only be produced in the zero-gravity conditions of space. In addition to its incredible strength--several times the strength and heat-resistance of titanium, Gundanium alloy is electrically non-conductive and cannot be detected by radar. However, this material is expensive and difficult to manufacture, making it unfeasible for mass production.
Gundanium is created through the most advanced refining, fusing, and deoxidizing techniques, which are only possible in space. The complex formula was first called GND, short for Genetic on Universal Neutrally Different Alloy. Later the suffix "-nium" was added to distinguish that alloy from other similar alloys that were being developed on Earth. Gundanium was still superior to the competition because of its zero-G creative process.
While many similar alloys were developed, no other compound is as immutable as Gundanium. The refinement process causes the alloy to become electrically neutral, making it ideal for use with Beam-type weapons, and as armor, the material is almost entirely resistant to charge. However, the extremely high cost of production makes it impractical for military use.
While it’s called an "alloy," Gundanium contains many non-ferrous metals and non-analyzed matter, meaning it is not a true metal. It is created in high-temperature plasma that can only form in zero-gravity. The compound is adjusted in nano-units, a process so precise that it can only be done in gravitationally stable Lagrange Points. The annealing process, which strengthens the alloy, is performed by electromagnetic waves from the sun. It is even rumored that the nuclei of the atoms themselves are modified within the Gundanium alloy.
There is no armor capable of defending against beam weapons. The Gundanium alloy used in the Gundams' armor and the Planet Defensors of the Mercurius and Virgos is highly heat-resistant and virtually immune to corrosion, but it's still not immune to beam attacks. It does, however, create an "anti-field" that repels beam attacks to some degree, reducing the damage delivered, but not stopping it outright.
Use in MS Production
Some intelligence indicates that OZ scientists experimented with using Gundanium alloy in MS creation. The very existence of Gundanium was kept secret, perhaps because it was a possible secret weapon for OZ. The five scientists who left the Tallgeese project took with them the knowledge of Gundanium, allowing them to create the Gundams that would later be the bane of OZ.
The creation of the Gundams took decades of work behind closed doors, due in part to the slow process of manufacturing Gundanium. This is evidence of just how long a process Operation Meteor was, with the Gundams being created before their eventual pilots were even born.
As shown on the computer screen during Quatre's exploration of the program used to construct Sandrock. This could make it a descendant of Gundarium used in the Universal Century Gundam Universe.