I believe we are looking at the same items as w...

I believe we are looking at the same items as we saw in the early MER Eagle crater photos, in soil surface views of small dark spheroid shapes, sometimes angular, sometimes out of round, with the platy peripheral bright ring, which in many had a series of rather well developed extensions, either lobed or pinnate. The very small OM photo item from the Phoenix landing site, which appeared similar, carries many of the same shape qualities. For a zone of extreme cold, that appears to have an active phase at some timing, either short in timing, or ongoing, and should be of interest to NASA for that reasoning. I am sure they believe they have the basic ideas in a 'box' somewhere. If we could pry open that container to peer inside for a day...

I did a very simple experiment yesterday, with no camera record as yet, using some dry ice(CO2 frozen to ice), and a half dozen varieties of Iron compounds, including Iron(III) Oxide Red, a very brightly colored red powder which is the 'reddest' of the reddish ruddy and darker iron compounds I tried. In a first try to view the basics of CO2 ice with the various items, in an Oxygen dominated, and very humid Earth type atmosphere, I sprinkled the powders in the dry ice, as might happen in a dust storm on Mars. The dry ice, immediately upon closing the transparent plastic container, began to extract the water vapor from the air, both inside and outside of the container, causing a surface of thick bright frost all over the powders and the plastic walls of the container which was in direct physical contact with the dry ice. I found that the bright red Iron(II) Oxide Red, had the greatest alteration of color and tonality. Why this is was may relate to the finer powder particle size of the powdered material, so caution in hearing this description is appropriate, but the red powder became nearly white and indistinguishable from the dry ice background after a few hours. As I had to leave the ice unattended for a half day, and returned to study the remains after sublimation of the ice, I found some of the bright red powder had 'reappeared' as a powder residue on the bottom of the container, alongside the other various colors and tonal variations of the other compounds which were tested. This may be a premature challenge, to suggest a particular compound to be more reactive or attractive to the water vapor and more altered in color and tone when 'iced' with water frost, but it is surely a subject of some scrutiny in the standard science labs studying Mars climatology and mineralogy. I intent to repeat the test later, with a camera setup, and a presence throughout the sequence for viewing the process. The results may or may not be appearing repeatable later.
The details in no way match the conditions of Mars, nor do the compounds involved exist in the detailed results of the MER, CRISM, nor other instrument results of Mars surface, but I couldn't resist a very simple check of the basics of altered appearances when frost and ices are present in Earth's 'wet' and very dense atmosphere.
One interesting idea from the basic observations is that the powders seem to have a nonreactive interaction with the dry ice, which I would expect, as the dry ice is a solid to gas active compound even on Earth, as compared to a water ice interaction which we might expect would be more active, and even allow for a physical attractive relationship to develop between the powders and the water ice. In the weather on Mars the various development of water frost and CO2 frost/ice should cause a large amount of differing terrain patterning, with thin or thick lamination of the materials, and other physical terrain building.
To think of the seasonal CO2 geysers, for example, as a source of darker materials, might require the action of water frost or molecular vapors being interactive with the soil chemistry rather than thinking only of the CO2 ice to vapor process. I suspect that while a driving column of gas could suspend particles in it, the CO2 is not the carrier of the darker material. It would be a active water frost/vapor process with the sequence which was active in the far polar region, north of the Phoenix landing site.
I hope this exposition on surmising basics of soil particle interaction with CO2 and water ice hasn't irritated many here, as I can imagine it is central to the processes in the Phoenix photos showing color and brightness variability from day to day, in the Phoenix region climate.
I'll present more of this in a separate topic in Mars 'Geology' on the marsroverblog, if the results are repeatable. The bright ice viewed in the Phoenix images looks very isolated and nearly pure ice I believe. It must be forming from a molecule by molecule ice block building process, which may have tendency to exclude impurities. Perhaps the process of expansion and ice building is a far better source of melt-able and usable water than any 'wet' liquid solutions of particle and ice could be forming if liquids were involved. If an exclusion of the particles were involved and active with the dry ice, CO2, and perhaps with the water frost substituting for the vacuosities of the sublimating CO2 ice, the water vapors may form replacement chambers or veinlets during seasonal changes. In the Phoenix area as a little warmer than the south polar area, the building process may be daily.
Certainly the items Horton was referring to have been active at some timing. Was it unique in timing, or ongoing during climate changes?
Will we find well separated ice throughout the Phoenix digs?
It is curious that Ferrous Sulphate(FeSO4*7H2O), with water bound, is pale green in coloration, on Earth in our climate and atmosphere. What about the Mars variation of the same compound?
Will the frost and vapor affect the soil, or sequester to building ice deposits?