Gemstones on Other Planets: Exploring the Possibilities

[Kerrie]

I have deep fascination with precious and semi-precious stones, as I do a lot of natural stone beadwork jewelry. There are so many beautiful stones (not just diamonds, rubies and sapphires either) that are on our earth, but someday may be completely gone. My question is, has there ever been any real consideration as to what stones lie on other planets in or not in our solar system? I just read an article on CNN about other carbon planets that may have a huge source of diamonds that our outside our solar system.

by the way, my favorite stones are charoite and rhodonite if anyone is interested

 

[Andre]

Where-ever landers have been, Mars, Venus the rocks were thoroughly analysed. Nothing about precious stones as far as I recall. But that would have been sheer luck I gues. Chemistry should be roughly the same anywhere, so a lot is possible. But don't expect to find diamonds on Venus, it's all burned. Some "C" of the CO2 in the dense atmosphere could have belonged to diamonds though, some billions of years ago.

 

[Ivan Seeking]

Is the center of Jupiter really an Earth-sized diamond as claimed by Arthur C. Clarke?

We don't really know...[continued]

http://www.astronomycafe.net/qadir/q2270.html

This may be out of date.

 

[Bystander]

As Andre said, chemistry is chemistry --- cosmic abundances of the elements aren't too variable, so in system, or elsewhere, you are going to be looking at a function primarily of mass of planetary nebula, its distance from system center of mass, and radiation flux from that center as it evolves. That said, you're probably familiar with some sorts of explanations for the formation of various gem materials, and can conclude that you ain't going to find petrified wood on dry planets, nor will you expect turquoise, azurite, malachite, tiger eye, or any other stones requiring aqueous weathering and diagenesis. The less well known metal oxides, zircon, rutile, whatever may not be stable on the gas giants (hydrogen is a great reducing agent).

You got specific questions?

 

[Kerrie]

hopefully this is in the right sub forum...i guess my underlying question would be, do we absolutely know that there aren't other beautiful (yes, a subjective term) stones elsewhere in our solar system? charoite was only discovered in 1978 here on Earth in siberia! it goes to show that as advanced as we consider ourselves, there still are possibilities.

 

[Bystander]

(snip) --- do we absolutely know that there aren't other beautiful (yes, a subjective term) stones elsewhere in our solar system? (snip)

"We" absolutely know that no one has done a "global" inventory of all possible mineral types, or of their forms for this planet, let alone every other planet --- i.e., no one has clue what sort of lovelies are yet to be found.

 

[Ivan Seeking]

Funny, this just came up in the news.

Diamond Planets: Rich Possibilities for Other Worlds
The solid planets in our solar system are made mostly of silicates. Rock, basically. A new study shows that planets around some other stars might be made mostly of carbon instead. Deep inside such worlds, where pressures are intense, the carbon would make layers of diamonds that could be miles thick.

The rich-sounding worlds are modeled after a certain type of space rock, known as the carbonaceous chondrite, which are thought to be broken bits of asteroids. Many of them have been collected on Earth.

"These meteorites contain large quantities of carbon compounds such as carbides, organics, and graphite, and even the occasional tiny diamond," Marc Kuchner of Princeton University said in a teleconference with reporters Monday evening from an extrasolar planet conference in Aspen. [continued]

http://www.space.com/scienceastronomy/diamond_planets_050208.html

 

[Bystander]

From the link: "The planets in our solar system formed from a disk of gas and dust left behind from the Sun's formation. In regions where there was extra carbon or a lack of oxygen, carbon compounds like graphite and carbides would condense out of the mix, instead of stone."

"Extra carbon or a lack of oxygen" is a bit of a stretch for current H/He "combustion" models for stellar evolution --- high carbon is more likely to be associated with "high" everything else but H and He --- 'tain't to say there aren't other possibilities, but "high C" is more indicative of age, and age is correlated with "high" abundance of other fusion "ash" nuclei as well as of C.

 

[Andre]

Ivan, that's a very precious link Much more precious than you can imagine. Exactly what I was looking for. I'm elated. A big help for the missing oxygen problem on Venus.

 

[Ivan Seeking]

I knew it would help. I posted that just for you.

 

[Bystander]

I give up --- what "missing oxygen?"

 

[Ivan Seeking]

I give up --- what "missing oxygen?"

Have you tried breathing on Venus lately?

Sorry...

 

[Andre]

Well, the missing oxygen problem pertains to the evaporated oceans of Venus. This is all part of the moist greenhouse model (Kastings et al) The intense solar IR radiation would split the H2O molecules. The H2 would gas out into space and the O2 would react with the bedrock. As there is only a fraction of both O2 and H2 left, this would only have been possible with a thin atmosphere since this process would die out at about 10% of the total atmosphere.

Now picture all Earths water in the atmosphere. I estimated that this would be a total of 270 atm. (Hpa). Or 270 kilogram of oxygen for every square centimeter. That's not nearly a match for the oxygen to react with the soil. And there is also some 86 Hpa CO2 on Venus so you'd expect a lot of oxygen not reacting and remaining in the atmosphere of Venus, so where is the missing oxygen?

 

[Bystander]

Well, the missing oxygen problem pertains to the evaporated oceans of Venus.

Let's call it outgassed water --- not too terrribly likely things ever cooled off to the point of condensing oceans.

This is all part of the moist greenhouse model (Kastings et al) The intense solar IR radiation would split the H2O molecules. The H2 would gas out into space and the O2 would react with the bedrock.

Okay.

As there is only a fraction of both O2 and H2 left, this would only have been possible with a thin atmosphere since this process would die out at about 10% of the total atmosphere.

None of this follows from any chemistry from any laboratory on this planet. I presume you're talking about "a fraction" of the hypothetical ocean here.

Now picture all Earths water in the atmosphere. I estimated that this would be a total of 270 atm. (Hpa). Or 270 kilogram of oxygen for every square centimeter. That's not nearly a match for the oxygen to react with the soil.

Integrate from surface to core --- you've got lots of iron to oxidize.

And there is also some 86 Hpa CO2 on Venus so you'd expect a lot of oxygen not reacting and remaining in the atmosphere of Venus,

Again, this doesn't follow from any chemical principles --- a CO₂ atmosphere might make a great fire extinguisher, but it doesn't modify the free energies (equilibria) of the oxidation reactions.

so where is the missing oxygen?

Attempting to determine any difference in total oxygen fractions of the planets from atmospheric compositions is meaningless given that one is two or three times the temperature of the other (moves chemical equilibria around a bit), the wt. fraction of oxygen in crust and mantle rocks for both cases is 45-50%, and that the atmospheres are very small fractions of the planetary masses, ppm for Earth and 100 ppm for Venus.

Bottom line: there is no "missing oxygen." Might be fun to look at the mass of C in Venus atmosphere and compare it to the estimated totals for Earth --- got to make a rather wild assumption that all C has been cooked from core, mantle, and crust on Venus.

 

[Andre]

Bystander

The dD ratio on Venus is about 10 times that of Earth suggesting that the outgassing of H2 did occur.

Kasting, Toon, Pollack, Bullock and Grinspoon have writting libraries full of that mechanism. I'm not going to refer to the fallacy of consensus, the moist greenhouse gas hypothesis has been given some thought.

Short recap:
Venus started as Earth. Initually the CO2 was like Earth weathered from the atmosphere. Then when the sun increased in strenght the oceans started to boil, causing moist greenhouse effect. Water dissociated as mentioned and finally the CO2 came in.
It's not my idea and I don't agree as well. Only the first two counts.

http://funnel.sfsu.edu/courses/gm310/articles/SciAm.GlobClimChngVenus.pdf

Our simulations suggest that the clouds initially won out, so that the surface cooled by about 100 degrees C. But then the clouds were slowly eaten away. Water diffused higher in the atmosphere, where it was dissociated by solar ultraviolet radiation. The hydrogen slowly escaped into space; half of it was lost
within 200 million years.

But what happened with the oxygen? Can we find so much rocks to react with a proportional amount of water? But if there were enough diamonds then it would have been no problem. The biggest gem burning in the solar system (trying to keep this on thread)

a CO2 atmosphere might make a great fire extinguisher

Exactly! So the process could not be complete as it is, provided that the CO2 entered the atmosphere in the same era. That's the problem for the moist greenhouse mechanism, that I was trying to convey

Might be fun to look at the mass of C in Venus atmosphere and compare it to the estimated totals for Earth

Exactly! Has been done. Same order of magnitude. Slightly more for Venus.

gotta make a rather wild assumption that all C has been cooked from core, mantle, and crust on Venus.

Reality may exceed our wildest imagination. Suppose that the whole planet was molten and radiating energy at a few thousand K, wouldn't the convection currents inside the planet and the atmosphere transport all the burnables along all the oxygen?

 

[Bystander]

(snip)Reality may exceed our wildest imagination. Suppose that the whole planet was molten and radiating energy at a few thousand K, wouldn't the convection currents inside the planet and the atmosphere transport all the burnables along all the oxygen?

This is where grade school comes back to haunt everyone --- "solid OR liquid OR gas" plus hints and intimations in high school and college that gases are NOT soluble in solids.

No one's found the videotape so we can't get instant replays of accretion from the original dust clouds --- got to do a lot by inference: accretion energy for Earth and Venus sized planets is enough to kick T to around 10⁴ K; this takes place in a cloud of hydrogen and helium, lot of conductive, convective and gas molecules greater than escape velocity type cooling processes; ²⁶Al abundance is significant, and furnishes a very high power heating effect for the early years of any planet.

For rocks smaller than E & V (Mercury, Mars, Pluto, our moon), it's been hard to say that there was ever complete melting as a result of accretion plus radioactive decay (part of what makes Mars so interesting). Gas giants have masses that prevent "degassing" of the planetary nebula --- melt and are either quenched by the gas bath, or insulated and retain very hot cores. E & V? Probably completely molten, "de-atmosphered" (missing ³⁹Ar) during the early stages --- any vapor species of relative molecular mass less than 40 (and possibly much higher) was at high enough T to exceed escape velocity. Is this a "total" degassing of the melt? No. All we need is 1 ppm dissolved nitrogen to produce the Earth atmosphere --- so, we leave 3-5 ppm dissolved in mantle rock and core --- we do lose a little over time. How much carbon do we have to "cook" from the accreted masses? Cosmic abundances rank H>He>O>C for the "top four." There is a boatload of C to burn from the mix. Earth is O,Al,Si,Fe,Mg,Ca,Na,K plus trace amounts of other elements rather than exhibiting a C content 1/3 that of O.

Rates at which "volatiles" are removed from melts --- equilibrium chemistry of high T melts --- "terra incognita." "What we see is what we got."

Should be possible to get a handle on order of magnitude of total "volatile" losses --- we have crustal heat flow measurements that aren't too bad. Attribute this heat flow to ⁴⁰K decay, and compare the total heat flow (total ⁴⁰K) to the amount that should be present in an Earth mass accumulation of material made up from accepted cosmic abundances --- should be somewhere around 1/10 to 1/3 of our potassium requirement; that is, not only are we missing enormous quantities of carbon, we're also missing enormous quantities of potassium.

(Edit: Restate this frontwards rather than inside out and sideways --- "An Earth mass with a composition mimicking cosmic abundance, less H, He, Ne, and other obvious volatile species, will contain 3-10 times the ⁴⁰K necessary to furnish the present crustal heat flow through radioactive decay.)

The other thing your "modellers" did was to "assume" or "assert" a couple things that no one is going to "assume" or "assert" --- atmospheres are derived from only one or two things, that once derived, they're immutable, and that Earth and Venus should have identical geological histories.

 

[Andre]

Thanks for your elaboration, Bystander it appears that Venus could have well be in this state since it's accretion, somehow having a different history than Earth and the heat is mainly 40K

A few remarks.

No one's found the videotape

I believe that video is torn to pieces and hidden in all archives between the fiction videos. Strangely enough only few of us seem to be looking for it in all the possible archives.

we have crustal heat flow measurements that aren't too bad.

let's see http://adsbit.harvard.edu/cgi-bin/nph-iarticle_query?1996LPI...27..169B&data_type=PDF_HIGH&type=PRINTER&filetype=.pdf :

Brown et al content that the thermal gradient of the oldest terrains (Tessera) had a thermal gradient that exceeded 25 degrees Kelvin per kilometer while the youngest feature, the Artemis Chasma, has a thermal gradient of below 4 degrees Kelvin per kilometer.

I would assume that with the 40K up this steep decline in thermal gradient over time is a little unlogical, compared with the lack of plate tectonics, hence we need all kind of curious hypotheses about waxing and waning crust thickness, while there is a single hypothesis available for all.

Perhaps we should take another video.