Lunar Platinum is the initial metal we use at Camp Demigod. It is rather like platinum but pulsates with a lunar glow. It works best at night on a full moon. It won't matter whether the moon is visible or not, the metal carries the light of the moon with it.
Whereas Majesterial Silver is used for light and delicate weapons like bows and crossbow bolts, Lunar Platinum is used for heavy weapons, like two- and single-handed swords, clubs, spears etc. Many people use it because swords are the main weapon of camp.
It was a gift from Artemis to the campers of Camp Demigod.