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Author Topic: What is this strange rock..its like sphere that's been cracked in half...?  (Read 12189 times)

Offline Bailey

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The rock resembles a sphere with obvious spherical layering and a definite central core, its also very heavy for its size but magnets have no reaction..its not man made and the half I have is not quite symmetrical but very close...

What is it?
« Last Edit: 04/12/2009 08:55:37 by chris »


 

Offline Bailey

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can i send a pic or two of this rock for everyone to check out...?
 

Offline neilep

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Sure, send it to me at my email address via my profile (click on my name 'neilep') and I'll upload it onto the site for ewe.
 

Offline neilep

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here is the piccy of the rock I have just received. I am posting it for bailey and here is his description !

    hi...here's the rock,on the other side its perfectly round and smooth,its has an outer crust about 6 or 7mm deep,the inner crust is also spherical.i hope this isnt too big to send,i dont know much about cropping etc,but i can send better pics if you want.id be really interested to find out what this rock is and how it was formed....




 

Offline Karen W.

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very cool rock...
 

Offline JimBob

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It is a concretion, probably sandstone. The black is iron oxide. Neil called me here in the US form the UK, got me out of a soft chair and DEMANDED I take a look at this and IMMEDIATELY post a reply. So now that I am missing another episode of some piece of junk or another, I am answering this.

I am rather tired and I will let some other hot shot tell you how this concretion was formed if they get to it before I get back to it tomorrow.

Neil Just sent me this - the font is actual size of the font in the email.

so, my goading has worked !! muauaauhh !! (evil laughter)


(Actually he didn't exactly CALL me. I received the email on my Smart Phone.)

 

Offline geo driver

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noice noice ive not a scooby but i loike it
 

Offline JimBob

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OK ---- I finally have had a minute to get my thoughts together.

This type of concretion is formed because of the iron in it. They are common in Monument Valley here in the US. They are also found in the Northwest of Australia. They are also found on Mars. These concretions form in a sandstone layer where iron rich water is stored. By this, I mean the water does not move much; it is in a rather static state. Usually, the sandstone layer is close to the surface where evaporation can occur. As water enters it brings in more dissolved iron the concentration increases.

Then there is a trigger - usually a hydrocarbons in the fluid system - that causes the iron to begin oxidizing, forming hematite. In the picture Neil posted, hematite is the shiny black-gray material.

To get a more coherent explanation see this link - http://en.wikipedia.org/wiki/Navajo_Sandstone#Iron_oxide_concretions_.28Moqui_marbles.29

In extreme condition, shinny hematite spheres can form. See this  page - http://en.wikipedia.org/wiki/Hematite - CLICK ON THE PICTURE on the right. It will give you a larger picture where you will see spheres of hematite. These form in sandstones, lake and ocean bottoms as well as being deposited by super hot water.

Neil, are you happy now?

Lastly -

WELCOME TO THE FORUM, BAILEY!
 

Offline neilep

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OK ---- I finally have had a minute to get my thoughts together.

This type of concretion is formed because of the iron in it. They are common in Monument Valley here in the US. They are also found in the Northwest of Australia. They are also found on Mars. These concretions form in a sandstone layer where iron rich water is stored. By this, I mean the water does not move much; it is in a rather static state. Usually, the sandstone layer is close to the surface where evaporation can occur. As water enters it brings in more dissolved iron the concentration increases.

Then there is a trigger - usually a hydrocarbons in the fluid system - that causes the iron to begin oxidizing, forming hematite. In the picture Neil posted, hematite is the shiny black-gray material.

To get a more coherent explanation see this link - http://en.wikipedia.org/wiki/Navajo_Sandstone#Iron_oxide_concretions_.28Moqui_marbles.29

In extreme condition, shinny hematite spheres can form. See this  page - http://en.wikipedia.org/wiki/Hematite - CLICK ON THE PICTURE on the right. It will give you a larger picture where you will see spheres of hematite. These form in sandstones, lake and ocean bottoms as well as being deposited by super hot water.

Neil, are you happy now?

Lastly -

WELCOME TO THE FORUM, BAILEY!



I'm so happy i've done a wee wee !!
 

Offline neilep

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This is the other side

 

Offline Bass

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You sure this isn't man-made?  Rusted cannon ball, perhaps?  or something similar?
 

Offline Bailey

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im sure its not(processed/refined) metal of any type.. it weighs 250g..about half of a 'bald' tennis ball in size if thats any help?
« Last Edit: 02/12/2009 08:53:54 by Bailey »
 

Offline Mazurka

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concretions are notorious for being misidentified...
 

Offline JimBob

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im sure its not(processed/refined) metal of any type.. it weighs 250g..about half of a 'bald' tennis ball in size if thats any help?



See, Bass?
 

Offline Mr. Scientist

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here is the piccy of the rock I have just received. I am posting it for bailey and here is his description !

    hi...here's the rock,on the other side its perfectly round and smooth,its has an outer crust about 6 or 7mm deep,the inner crust is also spherical.i hope this isnt too big to send,i dont know much about cropping etc,but i can send better pics if you want.id be really interested to find out what this rock is and how it was formed....





It looks as though the outer compositional lines are granite-like almost. The spherical shape could have been just a natural wearing down of water... But the center looks as though it contains some iron... near the center. To try and test it magnetivity, have you applied any magnet to it, to see how the stones magnetite qualities are?
 

Offline chris

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Jim - why do these things form spherically?
 

Offline Bailey

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magnets do not react at all mr scientist.. it was one of the first things i did when i found it..
« Last Edit: 04/12/2009 10:25:56 by Bailey »
 

Offline JimBob

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Jim - why do these things form spherically?

Well sonny, let me light my corn-cob pipe and tell ye a little story - ops, wrong forum.

The shape is due to the structure of hematite crystals. The "class" of their crystal structure is know as triclinic. This  crystal form often occurs in a crystal "habit" or structures that are called botrioidal - grape-like.

The picture below is grape-like hematite from the Wikipedia page on "hematite" It shows how hematite form spheres. It can form speres such as these in sandstone with sandstone in the crystal matrix.





If you magnify the area outlined in blue on this picture above, you will see how these smaller crystals form the spheres. This structure is also seen in the rock Baily posted.



 

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