The purity is an issue.

来源: 于 2012-09-21 09:26:54 [博客] [旧帖] [给我悄悄话] 本文已被阅读：次

Gold itself is very stable in the air, or even in dampy air.I remember only a mixure of 3 strong acid can disolve gold. However, most of gold are not pure. That's why with time-goes, it loses its shinning.

Silver is much easily to be oxidated.