Light blue aluminium.
Is orange bronze really that unusual, given these?
Just want to mention, by the way, this is what uranium looks like:
This is what tungsten looks like:
This is iridium:
notice how they all look exactly the same, ignoring the shaping and polish differences? They're pretty much all indistinguishable from eachother, all nondescript iron-gray metals. If Greg went for realistic color schemes for his metals, 90% of them would be indistinguishable from iron.