Spheres are concreations. Are they are hematite?

ERRORIST · 2004-03-03 02:00:02

What if the spectrometer finds out they are hematite?? Could they then be fossils? Lots of water is involved we now know.

GraemeSkinner · 2004-03-03 02:35:40

Do you mean if they are hematite could there also be signs of life in the past?

ERRORIST · 2004-03-03 13:14:07

Possibly, or are some fossils on earth made of hematite? Could these have been hatching out of the spheres?

[http://www.space.com/php/multimedia/imagedisplay/img_display.php?pic=hf_mars_rotini_040301_02.jpg&cap=Opportunity's%20Microscopic%20Imager%20found%20this%20intriguing%20object,%20lookingmore%20like%20Rotini%20pasta.%20Its%20odd%20shape%20has%20stirred%20up%20Mars%20researchers,both%20inside%20and%20outside%20of%20the%20NASA%20Mars%20Rover%20Exploration%20team.%20Whetheror%20not%20this%20object%20is%20related%20to%20biology%20has%20prompted%20a%20variety%20ofviews.]http://www.space.com/php....fviews.

Marineris Sauce · 2004-03-18 00:20:31

Here it is folks! Is this the final word on the Martian blueberry spherules?

[http://www.space.com/missionlaunches/ma … 40317.html]Hematite's the word!

ERRORIST · 2004-03-18 11:52:41

Hematite forms in hexagonal formations, unless they have formed a fossil through diagenisis. These are not Hexagonal formations. The only thing that is left since they are hematite is a fossil. They are fossils of some sort.

It just doesn't make sense they are not hexagonal in form like on Earth if they are forming in the manner they are saying.

Shaun Barrett · 2004-03-18 19:11:23

Hi Errorist!
I think I see what you mean. But maybe haematite only forms in geometric shapes, like flat-sided hexagons or octagons or whatever, if it is pure.
These martian spheres are formed in an environment which includes many solutes, including compounds of sulphur, magnesium and chlorine.
Maybe you're thinking of pure crystals of haematite, whereas these are impure and therefore described as concretions; solidified from a mixture of compounds but with haematite merely the predominant ingredient(?).
???

If spherical mainly-haematite concretions could only arise as a by-product of biology, I'm sure we would have heard more about it by now.

ERRORIST · 2004-03-18 20:14:45

Yea,but they wouldn't let that information out would they? It would prove the existance of a supreme being. Right? I don't think the world would be ready for such hypocrisy??

Shaun Barrett · 2004-03-19 00:14:18

Errorist:-

It would prove the existance of a supreme being. Right?

I don't see how. Life arose here on Earth and yet the existence of God is a long way from proven.

ERRORIST · 2004-03-19 10:05:01

It is written in Genisis 2.0

Rxke · 2004-03-19 12:47:51

diagenesis. 1. n. [Geology], ... Grains of sediment, rock fragments and fossils can be replaced by other minerals during diagenesis. ...

So not necc. fossils...

ERRORIST · 2004-03-19 13:35:31

Grains of sediment, rock fragments grow into hexagonal, and Tigonal formations though.When fossilized it takes on the form of the organism. These formations are not trigonal or hexagonal.So you can see what is left????

C M Edwards · 2004-03-19 14:59:14

Iron-rich minerals deposit all the time on Earth. However, most of that recently deposited iron is not hematite. Most of the hematite ore found on Earth is found in formations dating from well before the cambrian period, so much so that geologists speculate that some event during this time caused a massive deposition of hematite in the world's oceans.

One such speculation is that the first introduction of oxygen by living organisms oxidized the iron in the oceans, depositing it all as rust and iron sulfides in a few million years. Another speculation is that iron-metabolizing microbes (similar to those known today) deposited the iron. However, all that is really known is that most of Earth's hematite formed relatively quickly, deposited in only a few geologic layers.

The satellite survey of the Meridiani area indicates that the hematite layer is very thin.

This means that Mars may have experienced banded iron formation just like Earth.

My guess is that it happened for the same reason.

C M Edwards · 2004-03-20 07:50:22

The elemental composition of the rocks in Opportunity's Eagle crater seems very similar -- almost identical -- to the elemental composition of the infamous ALH 84001 meteorite, which is the meteorite that sparked the "Life discovered on Mars" debate a few years ago. Most of their mineralogical differences can be entirely accounted for by thermal decomposition, such as might be expected in an asteroid impact sufficient to fling ALH 84001 into space from the Martian surface.

I would be willing to bet that all the magnetite found in ALH 84001 was originally hematite that got baked during the original ejection of the meteorite.

I would also be willing to bet that, in addition to the obvious "blueberries", the rocks at Eagle crater also contain microscopic hematite granules (just like those that presumably used to be in ALH 84001). I suspect the whole bunch of rocks formed in similar fashion.

What are the smallest hematite concretions Opportunity can see? What is their size distribution?

I think its time to go back and look more closely at the pictures from Opportunity's "microscope".

ERRORIST · 2004-03-20 09:33:27

CM,
Good idea let me know what you find????

C M Edwards · 2004-03-31 12:05:55

I’ve done a little preliminary analysis of some of the soil sample micrographs, looking for a size distribution pattern in the hematite blueberries at Eagle crater. The following mosaic is a good example of some soil micro-photos by the Opportunity rover:

[http://marsrovers.jpl.nasa.gov/gallery/ … 2R1_br.jpg]http://marsrovers.jpl.nasa.gov/gallery...._br.jpg

and this non-micrograph picture of the “Berry Bowl” site was interesting as well:

[http://marsrovers.jpl.nasa.gov/gallery/ … 0R1_br.jpg]http://marsrovers.jpl.nasa.gov/gallery...._br.jpg

It’s been noted that the size distribution of these hematite concretions is not uniform or balanced. There appears at first glance to be a distinct upper and lower limit to their size throughout the Eagle Crater site, with the average size of the globules being closer to the upper limit than the middle of the range.

I think that there is indeed a consistent upper limit to the size of the hematite blueberries, which is on the order of about 3mm but actually varies significantly from sample to sample. The largest blueberries exceed 5mm but those are quite rare. The average is between 2mm and 3mm, despite the fact that the median value is usually closer to 1.5mm.

There is an observable lower limit in several of the samples, but not all. Further, this lower limit is not consistent from sample to sample. I think we can attribute this to two effects: 1) resolution limits and other artifacts in the images which make my sampling technique of sliding a ruler around my screen unable to discern the smallest particles, and 2) size separation of particles due to saltation in the soil samples.

This link is an article discussing size separation of particles in a collection of vibrated (or windblown) granules:

[http://jfi.uchicago.edu/~jaeger/group/p … Nature.pdf]http://jfi.uchicago.edu/~jaeger....ure.pdf

The graph at the beginning of the article is very interesting, as it indicates what would be necessary for large particles (like the hematite blueberries) to separate and rise within the surrounding sand grains as the soil is blown along the surface. This data suggests that the largest blueberries would rise to the top of the windblown sand over time as they were carried along, with the smaller blueberries remaining buried, thus segregating them according to size and concentrating the larger blueberries on top. It also suggests that the blueberries are either significantly heavier than the smaller particles that comprise the rest of the windblown sand or (an intriguing possibility) a dozen times lighter than the surrounding sand.

How large this difference in density is may provide an additional clue to the composition of the little spheres. For example, if they are porous, their distribution will vary slightly from that of solid hematite granules.

Hmm...

ERRORIST · 2004-03-31 12:22:02

Still can't rule out biological in origin can we????

C M Edwards · 2004-03-31 14:10:50

No.

In fact, I would dearly love to rule it in. However, all I can tell you about is size and approximate relative density.

The size distribution is fairly sharply limited to 5mm. The separation of sizes during saltation should leave the largest particles on top, and there just aren't any larger than 5mm. This suggests that something prevented the growth of hematite blueberries larger than 5mm.

As for the density, the average density of solid hematite is 5.3 g/cc, while the average granular density of silica sand is 2.6 g/cc. Solid hematite grains are twice as dense as solid silica sand grains. So, according to the chart in the article, the smallest grains of solid hematite we should see always on top of a windblown mix of sand and hematite are those whose size is at least 25 times that of the average sand grain. Anything smaller than that would be mixed in evenly with the rest.

C M Edwards · 2004-03-31 14:14:11

And no, I don't know that the smaller grains are silica sand. I just used something with a known density for comparison to show how the blueberry density could be estimated.

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Re: Spheres are concreations. Are they are hematite?

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Re: Spheres are concreations. Are they are hematite?

#3 2004-03-03 13:14:07

Re: Spheres are concreations. Are they are hematite?

#4 2004-03-18 00:20:31

Re: Spheres are concreations. Are they are hematite?

#5 2004-03-18 11:52:41

Re: Spheres are concreations. Are they are hematite?

#6 2004-03-18 19:11:23

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#7 2004-03-18 20:14:45

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#8 2004-03-19 00:14:18

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#9 2004-03-19 10:05:01

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#10 2004-03-19 12:47:51

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#12 2004-03-19 14:59:14

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#13 2004-03-20 07:50:22

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#14 2004-03-20 09:33:27

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