Imperial Gold is a blessed precious metal used by Roman demigods. It is forged at Camp Jupiter in their sacred temple. Chrysaor was the first to wield an Imperial Gold blade, but is not credited for it in the myths.
Imperial Gold is a very rare metal, as it was used a lot in Ancient Rome. They still use it in New Rome but not as much, as it is very rare. It is never mentioned that the Greeks ever wielded this type of metal, sticking to Celestial Bronze instead. . The ore is specifically deadly to monsters , immortals, etc. In addition, it is extremely bad if it breaks, causing mass destruction, as shown in The Lost Hero, when Jason Grace's Imperial Gold weapon was broken.