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Theropod you were spot on when you identified the egg as a concretion.


Dear Mark,
I’m sorry to disappoint you but I have identified you specimen as a concretion and sadly not a dinosaur egg. I’ve attached a sheet which explains a little bit and this website also explains concretions: http://australianmuseum.net.au/Concreti ... and-Geodes

It’s difficult to tell without feeling the weight and surface of it, but I suspect that there is iron in your concretion. I hope this is of interest and not too disappointing.

Best wishes,
Luanne Faulknall
Earth Sciences Identification and Advisory Officer
Angela Marmont Centre for UK Biodiversity
Natural History Museum,
Cromwell Road, London
SW7 5BD, UK .




Stones and Markings Mistaken for fossils.
© Trustees of the British Museum (Natural History) 1974

The term fossil was originally applied to any stone dug out of the ground (Latin: fossilis, dug up), and included mineral crystals. However, the term is now applied only to remains of plants and animals of past ages preserved in rocks or sub-soil. Pieces of rock weathered into peculiar shapes, and certain structures of inorganic origin are sometimes mistaken for fossils.

Dendritic markings
Ground-water usually contains traces of iron and manganese, and when it seeps along cracks in a rock, it may deposit a film of the oxides of these metals in a fern-like pattern (pyrolusite, an oxide of manganese, is the commonest). When these ‘dendrites’ are seen on broken surfaces of rock they are often erroneously thought to be fossil plants. During the deposition of silica as agate in the steam-cavities of lava, certain impurities may crystallise in branching or dendritic fashion and appear as moss-like structures in the surrounding translucent silica.

Concretions
Ground-water in sands and silts becomes saturated in places with iron salts. The iron is thrown out as oxide, which forms ironstone concretions. These generally have concentric layers and are often hollow (hence ‘box-stones’). They may contain loose centres of hydrated iron oxide (limonite) and are then called aetites or ‘eagle stones’. These are sometimes mistaken for fossil nuts or fruits.

Septarian nodules.
Muds laid down on the sea floor, which become clays and shales, often contain carbonate of lime in solution. This tends to solidify around centres, forming concretions which harden on the outside. As they dry out, they shrink from the centre outwards forming internal radiating cracks which become filled with calcite (crystalline carbonate of lime), producing partitions or septa (hence ‘septarian nodule’). When partially weathered they resemble turtle shells (hence ‘turtle-stones’); if the concretionary material is weathered out honeycomb-like structures (‘melitaria’) are left. They are common in clays (e.g. the London Clay). Similar stuctures may be formed of iron carbonate (e.g. the ‘beetle-stones’ of the Coal Measures, so called from the pattern shown when they are split), or of pyrite with quartz septa.

Mineral ‘beef’.
Carbonate of lime in solution in beds of shale may crystallise along the bedding-planes forming seams of fibrous calcite crystals at right angles to the bedding. These are popularly called ‘beef’ or ‘horse-flesh’ because of their fibrous appearance. Broken pieces resemble fossil wood. They are common, for example, in the Liassic shales of Lyme Regis.

Cone-in-cone structure is also found in limy shales. It consists of thin layers of close-fitting cones, each composed of fibrous calcite crystals. The axes of the cones and fibres are at right angles to the bedding. It is believed to be the result of crystallisation under high pressure. Somewhat similar structures are found in coal.

Styolites are thin wavy layers of insoluble impurities found in limestones (e.g. the Chalk and in polished surfaces of marble) with an average direction parallel to the bedding and sometimes showing vertical striations. They are believed to represent thicknesses of rock which have dissolved under pressure. They may be mistaken for fossil wood.

Fibrous Barytes. Barytes (sulphate of barium) may be deposited in a fibrous crystalline form in cavities in limestones from barium-bearing solutions. It is heavy, and may be mistaken for fossil wood. It is sometimes called ‘cawk’.

‘Figure-stones’. Flint nodules, concretionary growths formed in the Chalk by the replacement of carbonate of lime by colloidal silica, sometimes have fantastic shapes; some may resemble the horn of an animal, another may look like the crude sculpture of a human figure. Natural breaks and weathering may have increased such resemblances, which are quite accidental. Other mineral substances are liable to become segregated in sedimentary formations as concretionary nodules of fantastic shapes, notably the soluble carbonates of lime and magnesia and colloidal substances such as iron hydroxide, phosphate of lime and hydrated aluminium silicates. Knobbly lumps of carbonate of lime formed by concretionary action in loam of the kind known as loess are popularly called ‘loess dolls’ in France and Germany. Curiously shaped nodules of claystone and clay ironstone in some clay formation are commonly referred to be country folks as ‘fairy stones’ (although the name is also applied to fossils and prehistoric stone axes).

Banded flints. In the formation of a flint nodule, the colloidal silica has sometimes been deposited rhythmically in bands, which differed originally in their water content. Differential weathering of the bands may cause such a flint to resemble a fossil work or part of a screw.

Pensioner,

Ah, I was afraid that was the case. I've seen other such shaped objects that were not, thus the need for you to have additional consultation. I thought the missing parts from one end were far too thick to be lost shell.

Still, this is a cool rock and would be interesting sawed in half.

RS

Piper,

I forgot to mention the other mechanical option of micro abrasion. Basically a tiny sand blaster these high precision instruments can speedily remove stubborn matrix. Again a skill one must gain by practice. A special chamber must be used to contain the abrasives and stone dust, with gloves like a radiation isolation chamber. Some of the abrasives can be expensive, but for final polishing work food grade baking soda is great.

Again, I recommend one look HERE'S for more info.

RS

theropod wrote:Piper,

I forgot to mention the other mechanical option of micro abrasion. Basically a tiny sand blaster these high precision instruments can speedily remove stubborn matrix. Again a skill one must gain by practice. A special chamber must be used to contain the abrasives and stone dust, with gloves like a radiation isolation chamber. Some of the abrasives can be expensive, but for final polishing work food grade baking soda is great.

Again, I recommend one look HERE'S for more info.

RS

Hi Therapod,
Thanks man, I saw that link and read the whole page. It's very helpful as always. Even has brand recommendations. It got me thinking of looking for Ice Age animals in gravel pits. I might have access to one this summer that my friend is digging up for fill. He said I could go look. For today I think I'm going to put the etching on hold. I really appreciate your help.
There's a real lot to invest in practice and money to do a good job of it I think. I'm still intent on figuring out the acid tests though. I need to get a little piece of definite Limestone so I can watch it fizz with my own eyes.
I'm intent on learning about the fossils and geology right now, and finding more fossils. They're both very enjoyable to me.

I'm not sure if you saw these pics a few pages backhttp://rational-skepticism.org/earth-sciences/help-identifying-a-rock-fossil-post-your-finds-t832-60.html#p54243Do you have a guess if those spots are fossil poop or baby sea urchin type animals, or neither? There are more fossils around the rock. I should be able to id the fossils on my own in due time, but if anyone alse wants to look, I'll be happy to share more pics.

The_Piper wrote:

theropod wrote:Piper,

I forgot to mention the other mechanical option of micro abrasion. Basically a tiny sand blaster these high precision instruments can speedily remove stubborn matrix. Again a skill one must gain by practice. A special chamber must be used to contain the abrasives and stone dust, with gloves like a radiation isolation chamber. Some of the abrasives can be expensive, but for final polishing work food grade baking soda is great.

Again, I recommend one look HERE'S for more info.

RS

Hi Therapod,
Thanks man, I saw that link and read the whole page. It's very helpful as always. Even has brand recommendations. It got me thinking of looking for Ice Age animals in gravel pits. I might have access to one this summer that my friend is digging up for fill. He said I could go look. For today I think I'm going to put the etching on hold. I really appreciate your help.
There's a real lot to invest in practice and money to do a good job of it I think. I'm still intent on figuring out the acid tests though. I need to get a little piece of definite Limestone so I can watch it fizz with my own eyes.
I'm intent on learning about the fossils and geology right now, and finding more fossils. They're both very enjoyable to me.

I'm not sure if you saw these pics a few pages backhttp://rational-skepticism.org/earth-sciences/help-identifying-a-rock-fossil-post-your-finds-t832-60.html#p54243Do you have a guess if those spots are fossil poop or baby sea urchin type animals, or neither? There are more fossils around the rock. I should be able to id the fossils on my own in due time, but if anyone alse wants to look, I'll be happy to share more pics.

Piper,

Yes, one can invest a good hunk of change in fossil prep tools and equipment. It gives one a whole new outlook of such works of masterful preparation such as "Sue", which the display version is a replica of the real bone. The investment in ones time to become an accomplished fossil preparator is staggering.

In the images you are referencing I what I am seeing is some internal partial replacements. The surrounding rock may have a good representation of the organisms in question, as they appeared (morphologically) before deposition, but you'll be looking at those in negative. I can't tell anything about those without the ability to see the 3D aspects of these molds. I think some people have tried making thin membrane casts and peeling these out after they've cured. These were then used to make a mold to cast replicas in Plaster-of-Paris. Needless to say that's a real pain in the ass.

RS

Aw poo. My fossil egg is no doubt a "concretion" thingy too then isn't it. It's pretty damn thick.

I'll try and take fotos of my items at the weekend.

Hi Therapod,
I think good fossil prep requires one to be a good artist. Or a dentist

In the images you are referencing I what I am seeing is some internal partial replacements. The surrounding rock may have a good representation of the organisms in question, as they appeared (morphologically) before deposition, but you'll be looking at those in negative. I can't tell anything about those without the ability to see the 3D aspects of these molds. I think some people have tried making thin membrane casts and peeling these out after they've cured. These were then used to make a mold to cast replicas in Plaster-of-Paris. Needless to say that's a real pain in the ass.

That sounds like a lot of dangerous work too. It would be cool to see little casts of the animals.
You should see the ones I found yesterday in the drainage ditch again hehe. One has the largest shells I've found yet, maybe 3 inches long
I'll share some pictures here soon.

I just learned a couple new lessons the hard way.
1. One rock I found yesterday is about football sized and dirty from the brook, and had mud in the crevices so I dunked it in a bucket of water, only to discover that some of the fossils have the consistency of dried mud and I undoubtedly lost parts of some.
So careless of me. I can barely handle the rock because it's so brittle.
2. I found an unidentified fossil about an inch and a half long in a rock that was laying on the ground cracked in 2 pieces. There is also a very detailed tiny round animal in the same layer, and the outline from the animals in the other layer( other half of the rock)
There was a little moss on the edge of the object that was recently exposed to air, and I tried to remove it with my thumb, pulling the fossil in half, with some sediment falling onto the table. It is also the consistency of dried mud/sand. Now it's ruined!
Lessons learned, investigate thoroughly before removing anything at all. Also, take pictures immediately for your own record in case it gets damaged.

Un-edited for clarity. Sorry.

Ok here are my things. All bought I'm afraid, never found anything myself I'll list what I was told they are above them, am not stating it as a fact.

Firstly the egg shell, outer curved section. Not easy to photograph I'm afraid


Inside section. There seems to be some membrane stringy thingy on the inside.


Mososaur Tooth



Spinosaurus Tooth



Mammoth Ivory



Dactylioceras Ammonite.


Little ammonite. About the size of a finger nail.


Lastly my little fishy.

Lycoptera from Liaoning in China, Yixian Formation, 145MYA (That's what it said on the ticket)



My geology items here

http://rational-skepticism.org/post71010.html#p71010


This is all my stuff on display


(Claws in the top left aren't real)

Another thought about the vinegar acid test...I've tried numerous random pebbles and ones that I think might be Limestone, all from my property, and have not yet witnessed any fizzing. Most of them form bubbles, but the bubbles remain on the rock. 2 or 3 actually bubbled out of a few pores for a while, but it was far from what I'd call fizzing.
I'm using straight 5% distilled vinegar without diluting it now.
I took a little bottle of vinegar outside with me and poured it onto various rocks out there, still no fizz.
I guess I don't have much Limestone around?
I've found more details about my locality. I 'm "probably" getting rocks from the "Allsbury Formation", but another map I found is a little more ambiguous. I read a paper written by a geologist about the area, but it still isn't clear enough to me to say.
According to the map where I found enough detail to locate my brook and property line, this is the description-

Primary rock type slate
Secondary rock type sandstone
Tertiary rock type conglomerate; graywacke

http://tin.er.usgs.gov/geology/state/sgmc-unit.php?unit=MESpu%3B0
That page is great.
Id'ing the fossils will help me of course. I'm working on that here and there, it's very hard work for a beginner. That's the fun part though. These creatures lived and died right here before the Permian extinction. I still find that amazing. Maine was located south of the equator at that time!
I was next door telling my friend about all the fossils, and looked in their drainage ditch and found 2 more immediately.
He said "oh yeah, cool" and offered for me to keep them. I put them back, for now
I wonder if this was a shoreline, because I don't seem to fail at finding fossils. Unless the whole ocean floor was littered with shells at that time?