Space/Science — HabitableZone

Space/Science » in reply to re: Rocks

Blue rocks in Nature?
Robert Clark — (archived)

Thanks for the great images and links. The green mineral olivine has been detected on Mars by the TES instrument on MGS.
And a released visible color image from THEMIS shows green areas in the image:

PIA03738: Candor Chasma on Mars, in Color
http://photojournal.jpl.nasa.gov/catalog/PIA03738

I don't think though that the green areas have been identified as of yet as due to olivine.

However, *blue* minerals are apparently a different matter. Here's what Carl Sagan said about it in his last book _Billions and Billions_ :

"Blue pigments are hard to come by in Nature. The rarity of blue rocks or blue sands on Earth and other worlds is an illustration of this fact. Blue pigments have to be fairly complicated; the anthocyanins are composed of about 20 atoms, each heavier than hydrogen, arranged in a particular pattern."
Billions and Billions,
Chapter 4, p. 53.

The anthocyanins Sagan explained are the pigments responsible for giving flowers such as roses and violets their colors.

I was sent an image of rocks in Antarctica with a bluish cast:

Rocks from Taylor Valley, Antarctica

http://sciforums.com/attachment.php?postid=302853


These seem more grey-blue than the rocks in the Pathfinder image though.

Some of the rocks on this page also seem to have bluish areas in them:

http://www.geocities.com/jghist/Glossary/glossary.html

However, I wrote the author of this page and he believes the blue areas in these rocks only appear that way because of lighting; they are actually closer to grey.

Finally Ralph Harvey believes ferrar dolerite provides an analogue to the Pathfinder rocks:

THE FERRAR DOLERITE: AN ANTARCTIC ANALOG FOR MARTIAN BASALTIC LITHOLOGIES
AND WEATHERING PROCESSES.
R. P.. Harvey1 1Dept. of Geological Sciences, Case Western Reserve Uni-
versity, Cleveland OH 44106-7216 (rph@po.cwru.edu).
Workshop on the Martian Highlands and Mojave Desert Analogs (2001)
http://www.lpi.usra.edu/meetings/martianhighlands2001/pdf/4012.pdf

Harvey informed me in an email that dolerite can be reddish on the surface through weathering but blue under the surface. However, in the image in this abstract showing the interior of a dolerite rock, it looks more grey than blue.
So I'm still looking for minerals that would match the blue colors seen in the Pathfinder rocks.

Bob Clark

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