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Old 07-03-2011, 10:44 PM   #7
Agemegos
 
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Join Date: May 2005
Location: Oz
Default Re: Dying Mars variant

Quote:
Originally Posted by whswhs View Post
With green, copper would be more likely, or magnesium (which I think is the analog of iron in the chlorophyll molecule).
That's right. Chlorophyll and haem are somewhat similar molecules, with iron giving haem its characteristic red colour, and magnesium taking the analogous place in chlorophyll, resulting in green.

Chromium compounds give a startling range of colours, partly because chromium is kind-of stable in a wide range of oxidation states. Chromium (II) is the one you would need in a close haemoglobin analog, and that tends to be not-all-that-stable-really and bright blue. The yellow pigments are mostly chromates, I think, with chromium in the (VI) oxidation state where it is chemically very unlike iron or magnesium (electron accepting rather than electron donating).

However, if you are in a world where the existence of the luminiferous aether somehow allows spaceships to take off from Earth's surface without monstrous rocketry, no-one is going to quibble much over the details of chemistry. And if they did, you could simply tell them that this chromate-rich respiratory pigment was only a functional analogue of haemoglobin, not a chemical analogue.
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