The Galaxy S6 and S6 edge sport sophisticated metal-and-glass chassis, and the glass cover of the casing comes in several hues to boot. You can get them in White Pearl, Black Sapphire, Gold Platinum, Blue Topaz (Galaxy S6 only) and Green Emerald (Galaxy S6 edge only).
Nobody mentioned anything about an eventual brown/bronze version for the Galaxy S6, though, but it appears as an option over at Samsung's UK site, as you can see from the screenshot. Granted, you can't really choose this color yet, so it might be a glitch, or, alternatively, Samsung might be readying to announce another color option later on, as it sometimes does.
Thanks for the tip, Zali!
source: Samsung UK