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Freeze thaw method advise


Strepsodus

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Hi. When I go fossil hunting in West Yorkshire I find concretions which are often full of plants but they never seem to split well when hit with a hammer. I therefore am going to try the freeze thaw method. As I don't want to use my freezer I intend to put the concretions in icy water and then boiling water. Would that split them? If so how long does it usually take? They seem to be a bit harder than the ones from Mazon creek.

Another question I have is can tupperware boxes hold boiling water? Will it melt or produce gasses?

Thanks,

Daniel

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Here's what Lori told me when I asked her:

"I spread them out in a single layer then cover them with water. Freeze solid, then run under HOT tap water. Sometimes you'll hear a little "pop", sometimes it comes minutes later. I let them sit at least 10 minutes before putting them back in the freezer.

NO HAMMERS, no matter how irritated you get. Some of them go in & out of the freezer 30+ times. I've got 2 from 2 years ago that still haven't popped. THOSE, I threaten to hit, but haven't yet. lol"

Info: Craig Hyatt, retired software/electrical engineer

Experience: Beginner, fossil hunting less than a year

Location: Eagle Pass, TX USA on the border with Mexico, hot dry desert

Formation: Escondido, Marine, Upper Cretaceous

Materials: Sandstone, Mudstone, Shale, Chert, Chalk

Typical: Thalassinoides, Sphenodiscus, Exogyra, Inoceramus

Reference: http://txfossils.com/Txfossils.html

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"....can tupperware boxes hold boiling water? Will it melt or produce gasses?"

That's what I am using. Boiling water does not melt it. I doubt it outgasses significantly.

post-20989-0-07892200-1469826477_thumb.jpeg

Edit: I'm told that most of the rocks in this tub won't crack open. There's something specific about Mazon Creek concretions. So I will periodically test different batches of rocks until I figure out what will work.

Info: Craig Hyatt, retired software/electrical engineer

Experience: Beginner, fossil hunting less than a year

Location: Eagle Pass, TX USA on the border with Mexico, hot dry desert

Formation: Escondido, Marine, Upper Cretaceous

Materials: Sandstone, Mudstone, Shale, Chert, Chalk

Typical: Thalassinoides, Sphenodiscus, Exogyra, Inoceramus

Reference: http://txfossils.com/Txfossils.html

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Daniel,

If you do not want to put concretions into your freezer, the best thing to do is wait until winter and freeze them outside, that is what I do. I place multiple 5 gallon buckets full of Mazon Creek concretions outside and let the freeze / thaw process work. It sometimes takes multiple seasons for them to open and the majority stay unopened. Since I have so many concretions, I do use a hammer when I am bored. I do have good luck, but as stated by others on the Forum, you can damage or destroy specimens.

Good Luck

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Daniel,

If you do not want to put concretions into your freezer, the best thing to do is wait until winter and freeze them outside, that is what I do. I place multiple 5 gallon buckets full of Mazon Creek concretions outside and let the freeze / thaw process work. It sometimes takes multiple seasons for them to open and the majority stay unopened. Since I have so many concretions, I do use a hammer when I am bored. I do have good luck, but as stated by others on the Forum, you can damage or destroy specimens.

Good Luck

So alternating liquid nitrogen and a blowtorch? Bad idea? :-)

Info: Craig Hyatt, retired software/electrical engineer

Experience: Beginner, fossil hunting less than a year

Location: Eagle Pass, TX USA on the border with Mexico, hot dry desert

Formation: Escondido, Marine, Upper Cretaceous

Materials: Sandstone, Mudstone, Shale, Chert, Chalk

Typical: Thalassinoides, Sphenodiscus, Exogyra, Inoceramus

Reference: http://txfossils.com/Txfossils.html

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Quick way is use a CO2 fire extinguisher to cool, takes seconds with beer, genuinely. 2kg ones aren't that expensive new if you look at safety suppliers and should last a while. You might find a refurbished secondhand even cheaper. Wear personal protective equipment of course :)

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"takes seconds with beer, genuinely."

And when the rocks and beer are ice cold, you throw away the rocks and drink the beer. I like the way you think! :-)

Info: Craig Hyatt, retired software/electrical engineer

Experience: Beginner, fossil hunting less than a year

Location: Eagle Pass, TX USA on the border with Mexico, hot dry desert

Formation: Escondido, Marine, Upper Cretaceous

Materials: Sandstone, Mudstone, Shale, Chert, Chalk

Typical: Thalassinoides, Sphenodiscus, Exogyra, Inoceramus

Reference: http://txfossils.com/Txfossils.html

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Daniel,

If you do not want to put concretions into your freezer, the best thing to do is wait until winter and freeze them outside, that is what I do. I place multiple 5 gallon buckets full of Mazon Creek concretions outside and let the freeze / thaw process work. It sometimes takes multiple seasons for them to open and the majority stay unopened. Since I have so many concretions, I do use a hammer when I am bored. I do have good luck, but as stated by others on the Forum, you can damage or destroy specimens.

Good Luck

I was told by an old timer Mazon Creek collector that he never uses a freezer to freeze/thaw and only uses the "winter season" method. He says the freezer can freeze them too fast causing possible damage to the nodules. He has an incredible collection so I know he speaks the truth. But I myself use the freezer as I am not that patient to wait until winter to start the freeze/thaw process. And I too sometimes break out the hammer and start sacking when thawing is slow.

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I'm just playing around with this. I switched in a batch of iron concretion looking rocks yesterday. I did have a thought while I was wandering yesterday. If you don't happen to live at a site with known concretions that pop, you might try picking up rocks that look promising *and* you see similar rocks that have split naturally. I know the desert temperature cycles to extremes because there are no large bodies of water to help regulate things. I see loads of chert with multiple conchoidal fractures lying about. I suspect some of these examples are from temperature stress. But, I don't see any fossils in the cores. The second most common example is iron concretion... or at least "brown rocks"... so I am trying those.

Info: Craig Hyatt, retired software/electrical engineer

Experience: Beginner, fossil hunting less than a year

Location: Eagle Pass, TX USA on the border with Mexico, hot dry desert

Formation: Escondido, Marine, Upper Cretaceous

Materials: Sandstone, Mudstone, Shale, Chert, Chalk

Typical: Thalassinoides, Sphenodiscus, Exogyra, Inoceramus

Reference: http://txfossils.com/Txfossils.html

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Hi. When I go fossil hunting in West Yorkshire I find concretions which are often full of plants but they never seem to split well when hit with a hammer. I therefore am going to try the freeze thaw method. As I don't want to use my freezer I intend to put the concretions in icy water and then boiling water. Would that split them? If so how long does it usually take? They seem to be a bit harder than the ones from Mazon creek.

Another question I have is can tupperware boxes hold boiling water? Will it melt or produce gasses?

Thanks,

Daniel

I would not expose them to boiling water. Using ice water then boiling them won't do much, but it can cause microfractures to spread throughout the piece and fall apart. This is a silly method(by no means am I insinuating you're silly or attacking you please understand this)that results in more harm than good.

I would get a small Tupperware (glade or w/e the UK equivalent is) soak them 5days and place in the freezer(at the bottom). I know you said you don't want to use it. If you're worried about harming the freezer, don't, it will be fine. Other than that, you'll have to wait for winter(or get a TARDIS☺).

Best regards,

Paul

...I'm back.

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Icy water will not work. The method takes advantage of water's density (which has to do with how the molecules move with their wide V shape). When water changes from liquid to solid, it expands significantly, so it can open cracks in the rock. If the water in the rock doesn't become ice, it's not gonna open.

I find that with soft rocks, wetting and rapid drying can remove a lot of matrix, but I've only tried it with inflated fossils and don't know if it would split concretions cleanly like the freeze thaw method.

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As the last two replies have stated, it is not just a temperature change from cold to hot that does the "popping" to open nodules like those found at Mazon Creek. Instead, it is the expansion of water during its phase change from a liquid to a solid that exerts quite an amount of pressure and can easily split rock. The contractors that repave roads in northern latitudes depend on this degradation due to the power of frozen water.

The key is to let the water saturate the nodule to be opened and then freeze it. I have no comments on the effectiveness of freezing outdoors during the winter verses using a freezer indoors (as we don't get much in the way of freezing temperatures down here in South Florida--thankfully). It is possible that the nodules might go through a nice series of freeze/thaw cycles in the winter if the temperatures cycle around the freezing point with warmer temps during the day and a hard freeze overnight.

I usually soak for several days followed by a day or two in the freezer. Once any water molecules within the nodule have converted to ice then there is no more work that the expanding water can do so leaving the nodules in the freezer for extended periods will not be of any benefit. Early on, I tried plopping the frozen nodules into hot (boiling) water to see if the thermal shock of a rapid rewarming might be of benefit but all it did was (as expected) to increase the amount of shattering instead of popping the nodule open cleanly on the fossil plane.

If you wish to make use of water's ability to infiltrate and push apart your nodule from the inside, then cycles of a longer soak alternating with a thorough freeze are going to be your best bet.

Cheers.

-Ken

P.S.: Don't forget to post photos of anything you find when your concretions do open.

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Hi. Thanks for the replies. I'll start collecting concretions for this winter; where I live it often gets below freezing.

Thanks,

Daniel

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I am not experienced with this method to open concretions and have a question.

Several members here on TFF have talked about collecting some concretions in their area and seeing what is in them. If the concretions in a particular formation had the mazon creek type of preservation it seems that some open ones could be found in the area. If there are no open concretions showing fossils would it be likely to find fossils in the unopened concretions of a formation?

Tony

Darwin said: " Man sprang from monkeys."

Will Rogers said: " Some of them didn't spring far enough."

 

My Fossil collection - My Mineral collection

My favorite thread on TFF.

 

 

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I am not experienced with this method to open concretions and have a question.

Several members here on TFF have talked about collecting some concretions in their area and seeing what is in them. If the concretions in a particular formation had the mazon creek type of preservation it seems that some open ones could be found in the area. If there are no open concretions showing fossils would it be likely to find fossils in the unopened concretions of a formation?

Tony

Count me in for this question. I'd also like to know if some minerals are more likely than others to harbor fossils *and* be poppers. The main rocks I see are sandstone, limestone chert and iron concretions. If you had to pick?

I just had another idea. I could collect a bunch of samples of each rock type and break them with my hammer. That might be a quick way to narrow it down.

Info: Craig Hyatt, retired software/electrical engineer

Experience: Beginner, fossil hunting less than a year

Location: Eagle Pass, TX USA on the border with Mexico, hot dry desert

Formation: Escondido, Marine, Upper Cretaceous

Materials: Sandstone, Mudstone, Shale, Chert, Chalk

Typical: Thalassinoides, Sphenodiscus, Exogyra, Inoceramus

Reference: http://txfossils.com/Txfossils.html

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Count me in for this question. I'd also like to know if some minerals are more likely than others to harbor fossils *and* be poppers. The main rocks I see are sandstone, limestone chert and iron concretions. If you had to pick?

I just had another idea. I could collect a bunch of samples of each rock type and break them with my hammer. That might be a quick way to narrow it down.

I would concentrate on the iron type of concretions, as most of the fossil bearing concretions I have seen are of that type. But then there are a lot of crustacean and ammonites in calcite type concretions-- so I do not know. I guess it is dependent on the formation.

Tony

Darwin said: " Man sprang from monkeys."

Will Rogers said: " Some of them didn't spring far enough."

 

My Fossil collection - My Mineral collection

My favorite thread on TFF.

 

 

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I am not experienced with this method to open concretions and have a question.

Several members here on TFF have talked about collecting some concretions in their area and seeing what is in them. If the concretions in a particular formation had the mazon creek type of preservation it seems that some open ones could be found in the area. If there are no open concretions showing fossils would it be likely to find fossils in the unopened concretions of a formation?

Tony

Hi. Where I collect most of the concretions are covered in a thin layer of Iron rich rock, which prevents water from getting inside. However, when the concretions loose the Iron rich layer they absorb water and often split open. I think most types of concretions can contain fossils but it depends on the location.

Daniel

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I am not experienced with this method to open concretions and have a question.

Several members here on TFF have talked about collecting some concretions in their area and seeing what is in them. If the concretions in a particular formation had the mazon creek type of preservation it seems that some open ones could be found in the area. If there are no open concretions showing fossils would it be likely to find fossils in the unopened concretions of a formation?

Tony

That's the logic I use when hunting mazon concretions in areas of mazonia/braidwood. I've roamed it all more than twice, and have identified areas that have blank concretions, and areas that produce more marine fossils than terrestrial, and vice a versa. Fortunately, all of that walking leaves me with a clear direction every time I go now.

Here's a helpful hint. When soaking your concretions give them several hours to soak. Walk up to the tray and lightly tap the side. As you do pay attention to the tiny air bubbles that may have formed, and are stuck, to the outside of the nodule. They'll rise to the top when you tap the tray. Continue to do so until they no longer form on the outside. They're ready to freeze.

I should note. Some nodules may not form air bubbles on the outside due to the density of the nodule, and/or the geological makeup of the outer surface. That depends on where they're collected.

Finding my way through life; one fossil at a time.

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  • 1 year later...

im actually thinking of doing this method with a fossil i just got. but im completly nervous that it might not be what i wanted since half of it is still encased

 

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2 hours ago, Squidsky said:

im actually thinking of doing this method with a fossil i just got.

Hi Squidsky (great name). The best, most complete, discourse on freeze/thaw is given in the 8/2/16 post by digit. This is easily accessed by scrolling up in this thread. To repeat - optimal results require that a nodule be soaked long enough for water to penetrate prior to freezing.

 

I assume you are asking about the tully you posted in another area. I have no experience with freeze/thaw and a partially opened nodule. Freezing and thawing (not unlike the slightly more primitive "whack and hope" technique) is a snarge shoot. It all depends on the internal structure of the nodule and its natural propensity to separate as one would wish, or not. However, my philosophy, unless dealing with a rare piece, is go for it. You can't make an omelet without breaking a few eggs. Your mileage may vary. Good luck.  

Human beings, who are almost unique in having the ability to learn from the experience of others, also are remarkable for their apparent disinclination to do so. - Douglas Adams, Last Chance to See

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36 minutes ago, snolly50 said:

Hi Squidsky (great name). The best, most complete, discourse on freeze/thaw is given in the 8/2/16 post by digit. This is easily accessed by scrolling up in this thread. To repeat - optimal results require that a nodule be soaked long enough for water to penetrate prior to freezing.

Nice to see that I've contributed something worthwhile.

 

This is probably what John is referring to:

 

http://www.thefossilforum.com/index.php?/topic/55231-mazon-creek-nodule-hoard-from-fossil-rock/

http://www.thefossilforum.com/index.php?/topic/67147-freeze-thaw-method-advise/&tab=comments#comment-706214

 

 

Cheers.

 

-Ken

 

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Thanks! I love squids!

 

 That's the one. The ppl I got it from said I could tap it open, but I've never tapped a rock open before. I always get nervous I might break something if I do it the wrong way. Esspecially since it was the only specimen not broken in half.   

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