Electrum

A gold alloy named in Elend's empire as "poor man's atium" and used by his Mistborn for one specific purpose: an Allomancer burning it cannot be read or pre-empted by an opponent burning atium. Like atium it is the Allomantic complement of gold; unlike atium it does not itself grant the future-sight that makes atium users near-invincible. MB1:HoA:Ch 3