All Metals Should Have Unique Aging Properties

I think it would be fantastic if all the metals in the game had aging properties similar to copper. For example, iron could rust when in contact with oxygen and moisture, such as during rain, or when adjacent to water. And gold could tarnish after frequent physical contact with mobs or players. And these properties could become even more interesting if Mojang were to introduce new metals and alloys, or iron and gold block sets of stairs and slabs.