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Trying to understand how when and why of fracturing


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Since there is very little traffic on this meteorite forum lately, I was thinking about pitching a topic in and see what others can tell me about it.  

My interest has to do with partial fracturing of the stone (not crust cracking).  Partial fracturing seems to be quite common occurrence in stone and even some metal.  For whatever reason and at some point in time, meteorites will fracture part way thru or several places part way thru but the mass stays together.  I'm wondering if some of it might happen as it is being ejected from its parent body?  Or, is it safe to say that it happens as part of the passage thru earth's atmosphere?  Some fracturing appears to be further modified/affected by the part of the flight after the mass disrupts .  Or at least that is my take after seeing some fractures that appear to be melted back together in spots and even bearing some secondary crust.  I know weathering can cause fracturing over time but even fresh falls have partial fracturing, right?  Go easy on me : )

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Entropy.

All rocks on all bodies in the entire universe eventually fall apart.

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Good question. 

I suppose "weathering" occurs everywhere, albeit slower out there floating in a vacuum.

There could be some thermal forces at play out there in the frozen space. One side in the sun and the other in the shade? 

Maybe centrifugal forces from violent spinning? Those stones probably haven't been just floating forever in space. At one point they were chaos and probably spun around for a million years before they finally stopped... If they ever did stop.

Whatever forces broke those rocks from the parent body was powerful stuff. So that is bound to create some fractures. Those rocks falling down on our heads started with a planet or an undifferentiated body getting smashed to smithereens.

Then there was slamming against our atmosphere and the subsequent deceleration. Maybe even a bolide event. That might crack a few stones before the fusion crust is formed. Or under a fusion crust as it is being formed.

The stones go from a deep vacuum to a pressurized atmosphere. That is a huge force. Especially along any natural fault lines. Under pressure our atmosphere would be forced into any small spaces as the stone got closer to earth.

Those stones have had a bazillion years to crack. They have had a lot of reasons to crack but not one good reason to stay together except the tiny bit of gravity that pulled them together in the first place.

 

 

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Bob touched on the idea that force or shock when traveling can cause cracks, also the composition of the rock will alone be more or less reason for cracks. 

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The hermit is right. Some meteorites just fall apart on their own. They were formed with a lot less gravity and with a lot less compressive force than the rocks on our planet. 

Chondrites just accreted together from their own gravity. The only thing that squoze them together was the gravity that their puny undifferentiated rock could muster. 

Earth rocks stratify and settle with mechanical action. And glue themselves together with chemical processes not seen on an asteroid.

Meteorites just accreted particles together as close as they could pull themselves and are only held together by molecular glue. They may be dense but the constituents aren't sized and cemented together like a terrestrial stone.

 

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3 hours ago, Bedrock Bob said:

Those stones have had a bazillion years to crack. They have had a lot of reasons to crack but not one good reason to stay together except the tiny bit of gravity that pulled them together in the first place.

 

 

A "bazillion" years? A "tiny bit" of gravity pulled them together?
:pop:
 

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17 minutes ago, Dakota Slim said:

A "bazillion" years? A "tiny bit" of gravity pulled them together?
:pop:
 

Yes Slim. A tiny bit of gravity.

A particle has very little. A big planet has a lot. A huge star has an immense amount of gravity.

The undifferentiated body that any chondrite might have originated from has much less gravity than the earth. So relative to the earth it was formed in just a tiny bit of gravity.

Terrestrial rocks are often formed under bazillions of pounds of force because of our gravity. Chondrite were formed under just a tiny bit of gravity.

...

Can you have an intelligent discussion about the topic or is being a huge pendejo your only game?

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6 hours ago, Dakota Slim said:

A "bazillion" years? A "tiny bit" of gravity pulled them together?
:pop:
 

 

6 hours ago, Bedrock Bob said:

Yes Slim. A tiny bit of gravity.

A particle has very little. A big planet has a lot. A huge star has an immense amount of gravity.

The undifferentiated body that any chondrite might have originated from has much less gravity than the earth. So relative to the earth it was formed in just a tiny bit of gravity.

Terrestrial rocks are often formed under bazillions of pounds of force because of our gravity. Chondrite were formed under just a tiny bit of gravity.

...

Can you have an intelligent discussion about the topic or is being a huge pendejo your only game?

I agree Slim, I'm not sure why it is you have to criticize everything Bob posts, I know you don't like Bob but this has to stop, consider this as a warning, I really don't want to issue another!! 

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10 hours ago, Bedrock Bob said:

 

...

Can you have an intelligent discussion about the topic or is being a huge pendejo your only game?

I merely saw a question from slim. Why so defensive and insulting , bob?

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Posted (edited)


Thanks guys for the info.  I appreciate the insight.  Partial fracturing has always intrigued me.  Maybe looking for partial fracturing when out hunting for specimens would be another good visual tool to help pick up possibles.  The weather is getting better in my neck of the woods.  I'm getting anxious to go out for a hunt.  

Edited by DarkSilicate
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