Electrum
Amber is the subject of some curious legends under this name, but there is also a metallic electrum, known to the French in modern times as Orbas. A cup of this metal, according to Pliny, has the property of discovering poison, by exhibiting certain semi-circles like rainbows in the liquor, which it also keeps sparkling and hissing as if on the fire. A black species of electrum or amber is the proper gargates of Pliny, and the jet of the present day. The occult virtues of electrum are of the tell-tale character.