Stromatolite?

[ydnar]

Please help me identify this find. All by itself in farmers field. Had xrd analysis (X-ray diffraction analysis )  done.

Results were text book mudstone composition.

Cut off piece with diamond saw. Water was black and it smelled swampy. 

Trace fossils can be seen.

 

[Andúril Flame of the West]

I do not see any readily identifiable fossils, but perhaps forum members more familiar with your area could provide a more educated analysis. As I commented on your other post, adding a general location or formation name (if you happen to know it) to this post would be extremely helpful. 

[Ludwigia]

3 hours ago, ydnar said:

Had xrd analysis done.

 

So could you please inform us of the results?

[ydnar]

It was actually xrf. (X-ray fluorescence)

MgO. 3.4%

AL2o3 15.9 %

SiO2  53.8%

K2o  2.2%

CaO. 4.5%

TiO2. 2.2%

MnO.   .11%

Fe2O3.  11.6%

 

[Fossildude19]

43 minutes ago, ydnar said:

It was actually xrf. (X-ray fluorescence)

 

 

 

I've added the spelled out words, as I had no idea what xrf or xrd are.

You might consider posting clarification when posting abbreviations or acronyms. 

[ydnar]

Acronyms are used regularly. Xrf is xray fluorescence. 

As I stated, the analysis was spot on with mudstone.

[Kane]

6 minutes ago, ydnar said:

Acronyms are used regularly. Xrf is xray fluorescence. 

As I stated, the analysis was spot on with mudstone.

Indeed they are, but given the mixed knowledge base here, it is considered a courtesy to use the full term first, and then subsequently use the acronym.

 

If you could provide an approximate location of the find, that might also prove beneficial -- particularly so when it comes to fossils where location is essential contextual information.  

[bockryan]

I don't see much of the banding that would be expected from a stromatolite on the cutoff picture, but could be the lighting. Location would be helpful, although being by itself in a field might mean it has been transported from somewhere else I suppose, either glacially or by people. 

[Fossildude19]

Anyways, it isn't a stromatolite. Not seeing anything other than possible ichnofossils here. 

[Coco]

Hi,

 

3 hours ago, ydnar said:

It was actually xrf. (X-ray fluorescence)

MgO. 3.4%

AL2o3 15.9 %

SiO2  53.8%

K2o  2.2%

CaO. 4.5%

TiO2. 2.2%

MnO.   .11%

Fe2O3.  11.6%

 

 

1 hour ago, Kane said:

Indeed they are, but given the mixed knowledge base here, it is considered a courtesy to use the full term first, and then subsequently use the acronym.

 

Kane’s right, I don’t understand your answer. Is it a chemical composition describing a rock ?

 

There are many non-English speakers on the forum, not to mention the understanding of acronyms.

 

Coco

[Ludwigia]

So, in summing up, you have a mudstone by the sound of it.

[Andúril Flame of the West]

7 hours ago, ydnar said:

Acronyms are used regularly. Xrf is xray fluorescence. 

As I stated, the analysis was spot on with mudstone.

This is a step in the right direction since fossils are often preserved in mudstone and similar sedimentary rocks but that does not guarantee a fossil. Sedimentary structures that may resemble a fossil can occur in mudstone and mudstone simply may not preserve fossils (conditions were not ideal for preservation, too old, etc.). 
 

As @Kane has already said, providing a general location would be helpful to have an idea of what formation this mudstone may have originated from (or if it was a glacial erratic as has been suggested). This would give members a shot at finding out whether your specimen may preserve a fossil. 

[Stingray]

I’m going with furnace slag without a location  especially since someone used XFR fluorescence on it. Although I reserve my right to guess at compressed clay by glacial pressure.

[Kane]

if it was found in SW Ontario, we may never know. The OP seems to be reticent on location. There are no outcrops here. At best, it is some glacial erratic. 

 

Found in a farmer's field really limits scientific value. It's an erratic rock with no clear in situ provenance. It's not a stromatolite.

 

Mineral composition won't mean much here. 

 

If you want stromatoporoids, make the drive to Formosa. The cap is all stromas. Many of them sub-aerial. Reach out and I can show you where.

[ydnar]

I would like to respond with more info about this find.

I tried to see if this rock material would effervescence but did not. I had xrf analysis done and confirmed it contained little calcium hence not carbonate but more so mudstone composition.

I found it in farmer field, sw Ontario. There are no rock or fossil outcrops in this area. It no doubt was a glacial placed rock from northern reaches of Canadian arctic.

The xrf analysis has major elements totalling 94 % with 6% unaccounted for. Since xrf cannot detect carbon element and when I cut open a piece organic carbon was present with every earthy swampy smell. My guess is the 6% being carbon in the form of a soluble organic carbon such as geosmin. As you know kerogen is another type of carbon compound associated with fossil but that material is insoluble.

You can see the organic carbon in the cut slice along with patches of yellow pyrite which is indicative of fossilzation.

One exposed patch on rock contains embedded spherical croinoids along with a bubbling surface suggesting oolids.

One end of the rock has series of holes which I believe are air vents where oxygen was expelled from this object.

If you view the rock on the side exposing some of the convex lamilae you can see impression of long lamilae columns extending from one end to other up to where vent holes located.

The stromatalite was covered with a mud material and fossilized as such.

At the end of the broken lamilae one can see trace fossils impressions quite clearly. Obviously these convex lamilae were grown by some type of bacteria...hence the trace fossil remnants.

This was a living organism at some time in past history. 

I find it amazing how after millions of years the 6% organic carbon it contains can release soluables and odours so fresh and distinct.

Thanks for the input to date.

[Kane]

Odours do not preserve. They simply don't. What you are smelling is likely the environment in which it was found. 

 

I'm not in the stromatolite camp yet. As you already know, our neck of the woods is mostly glacial erratics. At best, in the London area, we have some rock dumps from nearby quarries (Ingersoll, St Marys, Woodstock) as backfill for storm water management ponds (SWMPs). Apart from that, there are erratics that come downstream as early as the upper Ordovician, but mostly Devonian "trash salad." 

 

From a scientific basis, any finds here are nominal if there is no connection to an in situ outcrop. Those need to be traced to a quarry to do stratigraphic analysis. I have been frequently frustrated in finding rare specimens in London without clear provenance, and the City outsources that work to companies like AECON that do not keep records. 

 

13,000 years ago, Lake London burst in the post-glacial event and poured about 500 metres of sand, till, and cobble, of which your farmer's field find was likely part of. 

 

Still not seeing convincing evidence of a stromatolite here. Welcome to the desert of SW Ontario fossils!  

 

[ydnar]

I can tell you I used a diamond tipped saw blade and cut off a piece you can see in attachment. The water was a blackish color during cut. The odor was quite overwhelming. It smelled like a swamp. As I stated...quite amazed this organic compound has been preserved so well inside this fossil.

A rock would not contain soluable organics, but a fossil would.

I see convex column lamilae from one end to other with holes protruding at end exactly where oxygen (by product) would be expelled from living bacteria. Remember with stromatolites you only see remnants of bacteria activity.

[Kane]

Again, odours will not preserve over hundreds of millions of years. That is not how fossilization works. 

[Ludwigia]

You might have to take into consideration that the bacteria which produced the geosmin, if that's what it is, are of recent and not fossil origin. That typical odor can often be smelled everywhere on the surface where the earth is fresh and moist. It would particularly interest me to see a good photo of the embedded spherical crinoids and the "bubbling surface" which you have mentioned above. I'm not able to discern anything of the like in the photos you've shown us so far.

[GeschWhat]

If the last photo is the cut surface, I bet you were smelling the pyrite as you cut it open rather than organics. At least this looks like pyrite to me. 

[jpc]

geschwhat has hit the nail on the head, as far as I can say.  Sawing pyrite, which is sulfur and iron, produces both black dust and a strong swampy odor.  And the yellow insides of the rock look that could be limonite, an iron mineral that comes form decompising pyrite.  I am no mineralologist but I have had a few experiences with pyrite and limonite.  

[ydnar]

This is why I spent money on xrf element analysis. This fossil contains 11% iron. Its not limonite. Limonite is a hydrated iron containing 40 to 60 % iron. This rock fossil's chemical analysis mirrors mudstone composition. This is fact.

Heating pyrite gives off sulfur which combined with oxygen and hydrogen in air produces hydrogen sulfides aka rotten egg smell. I did not smell rotten eggs.

I smelled earthy swamp. Big difference.

Pyrite is evident by its distinct cubic crystal structure.

See pics attached.

Also showing crinoids...ooids and bubbling surface as requested by others.

Would this fossil having possible soluable organics be of scientific interest??

 

[DPS Ammonite]

Some of the organic swampy smells may be from living microorganisms that live in the outer layers of porous rocks. A lot of the limestones that I treat with acid have an earthy smell. A black goopy sludge is left behind after the acid reveals the chert fossils. The black is probably the remnants of microorganisms in the rocks such as bacteria, molds, fungi and lichen.

[Kane]

Still not a stromatolite.  Not in situ, so scientifically worthless. Time to move on. You found a good chunk of our Devonian trash salad. No significance at all. Good luck on your future hunts!

 

 

[Ludwigia]

I agree with Kane. I can't distinguish anything of significance in your fuzzy photos.