Lorica plumata, or "feathered armor", was a style of ancient Roman officer's armor which incorporated elements of chain mail (lorica hamata) and scale mail (lorica squamata) armors. While scale mail is generally constructed by sewing scales onto a leather or cloth backing, the lorica plumata was made by painstakingly weaving the drilled tops of thousands of tiny scales into a very fine chain mail mesh.
Armorers would often use two different types of metal scales in a single piece, giving the armor its "feathered" appearance. Brass and tin were common (though it's possible that the "tin" scales were merely tin-plated brass). While there is some debate as to the effectiveness of the armor, it is generally agreed that it was rare, beautiful, and very, very expensive.