The American Palladium Eagle is the official palladium bullion coin of the United States. Each coin has a face value of $25 and is composed of 99.95% fine palladium, with 1 troy ounce actual palladium weight.
Image: 2017 $25 Palladium obverse
Image: 2017 $25 Palladium reverse
Palladium is a chemical element; it has symbol Pd and atomic number 46. It is a rare and lustrous silvery-white metal discovered in 1802 by the English chemist William Hyde Wollaston. He named it after the asteroid Pallas, which was itself named after the epithet of the Greek goddess Athena, acquired by her when she slew Pallas. Palladium, platinum, rhodium, ruthenium, iridium and osmium form a group of elements referred to as the platinum group metals (PGMs). They have similar chemical properties, but palladium has the lowest melting point and is the least dense of them.
Palladium
Palladium(II) acetate
Platinum-palladium ore from the Stillwater mine in the Beartooth Mountains, Montana, US
Sulfidic serpentintite (platinum-palladium ore) from the Stillwater mine in Montana