Talk:Desert varnish

"one of fourteen"
Just deleted "It is one of fourteen different types of rock coatings." from the lead paragraph. What are the other thirteen? Is there an article in the wikipedia describing them? __68.116.168.148 (talk) 07:02, 20 February 2009 (UTC)

Life-form?
The article Shadow biosphere seems to be hinting that desert varnish might be (or might be claimed to be, by some) a form of life. Perhaps some information on this could added here? 86.134.117.67 (talk) 16:37, 2 April 2012 (UTC)


 * Agreed: The action of slow-growing microorganisms is essential for the formation of varnish. Just Google ("desert varnish" OR "rock varnish") hyphae and you'll see. Fjados (talk) 12:03, 7 April 2012 (UTC)


 * There doesn't seem to be much of a "smoking gun"; mostly speculation:
 * Carol Cleland, a philosopher of science at the University of Colorado (Boulder), argues that desert varnish, whose status as living or nonliving has been debated since the time of Darwin, should be investigated as a potential candidate for a shadow biosphere.

http://www.astrobio.net/index.php?option=com_retrospection&task=detail&id=2161
 * "The obvious place to begin is with known puzzling phenomena, such as desert varnish, that are difficult to explain in terms of familiar life and yet also difficult to explain in terms of abiotic processes."

http://www.astrobio.net/pressrelease/4071/
 * NASA scientists are seeing new evidence that suggests traces of water on Mars are under a thin varnish of iron oxide, or rust, similar to conditions found on desert rocks in California’s Mojave Desert.

Kortoso (talk) 23:35, 23 January 2014 (UTC)


 * Tentatively agreed: The "status as living or nonliving has been debated since the time of Darwin" bit is the missing link here. Where are the sources?  Debated by whom?  WHat background does a "philosopher of science" have that makes her view relevant?  There are two quotes, plus one assertion about NASA, in Kortoso's comment above, but only two sources, BTW.  I agree that this should be covered here if reliable sources support the view that the hypotheses are taken seriously enough to mention here without triggering WP:UNDUE or WP:PSEUDOSCIENCE concerns, but it needs to be done properly. And there are at least four hypotheses at work here: 1) Desert varnish is partly produced by life forms; 2) desert varnish is a life form; 3) desert varnish is a life form unrelated to others on earth and may have an extraterrestrial origin, e.g. from rocks knocked by meteorite impacts off of Mars and fallen later to earth as meteorites themselves; 4) life on Mars and perhaps other planets and moons might be most likely found in their equivalents of desert varnish.  — SMcCandlish ☺ ☏ ¢ ≽ʌⱷ҅ᴥⱷʌ≼  11:52, 6 September 2014 (UTC)


 * Disagreed This is probably adequately addressed in "This significant enrichment is thought to be caused by manganese-oxidizing microbes (mixotrophs) which are common in environments poor in organic nutrients." Kortoso (talk) 17:00, 8 September 2014 (UTC)

clay?
one section says that research has found that desert varnish is not clay. the next section says that it is mostly clay. how to resolve this discrepancy? Euglossine (talk) 19:32, 17 October 2021 (UTC)

Wildly out of date
The latest article cited on this topic, which has been a matter of intense debate for decades, is from 2009, and this is cited as if it were the last word.

It would be great if someone with the relevant expertise were to draw upon these two more recent articles -- one of which summarizes the scientific debate across the years -- in order to provide a more updated overview of what we know and don't yet know:

An ecophysiological explanation for manganese enrichment in rock varnish (published 22 Jun 2021 in Proceedings of the National Academy of Sciences volume 118 issue 25)

Shining light on photosynthetic microbes and manganese-enriched rock varnish (published 13 Jul 2021 in Proceedings of the National Academy of Sciences volume 118 issue 28) — Preceding unsigned comment added by 2601:185:8300:D70:647E:FDE2:12EE:6686 (talk) 23:26, 4 April 2022 (UTC)