Freeze Thaw And How Long Does It Take?

[Raistlin]

I bought some Mazon Creek nodules and have been trying the freeze/thaw method on them.

I leave them in for about a week or more and then out for a few days until they are thawed and back in again. I whacked one and it sort of split but not in half. I did not notice anything in it yet but put it back with the others.

Am I supposed to whack them from time to time to cause small cracks or does it happen on its own? How long does this take? I have been doing this for a few months now (2 maybe a bit more).

Do I just need more patience?

[Auspex]

They can sometimes strain one's patience (and even then be devoid of a recognizable fossil).

Use The Force (but not the hammer)

[ZiggieCie]

Here is a link to digits recent posts on mazon creek nodules and his work on splitting them. I think you will find it helpful.

http://www.thefossilforum.com/index.php?/topic/55231-mazon-creek-nodule-hoard-from-fossil-rock/?hl=%2Bmazon+%2Bcreek+%2Bnodules

Edited June 30, 2015 by ZiggieCie

[Raistlin]

Oh, thanks.

[digit]

The freezing portion of the freeze/thaw cycle is what should cause the popping of the nodules. Make sure they have been well soaked in water for several days or weeks. You want the nodules well saturated with water. The nodules should be fully frozen in your freezer in a day or two (no use leaving them in for much longer than this as it will have little extra effect). When I take my box of rocks from out of the freezer I usually fill the bin with water from the hose (outside next to my garage). I let them thaw for a couple of hours and then use a jeweler's screwdriver (flat blade) to help peel off any shale layers surrounding the concretion. A bit of light tapping with a hammer is sometimes useful to crack this outer shell of shale to help them peel out of these layers. Once you are down to the solid concretion inside (after all the shale layers seem to have been peeled away) then it is just time for nice long soaks in a bucket of water to try to saturate the siderite ironstone concretions with water alternating with a few days in the freezer. I have a 5-gallon bucket of nods so I can keep most of them soaking except for a few days in the freezer. After a few cycles I will give some gentle taps along the edge to try to entice a sticky nodule to pop but don't get too aggressive or you'll end up with shattered puzzle pieces. Many times there are old transverse cracks in the nodule which will fracture first. This may allow you to see inside the nodule a bit to determine if there is a good quality fossil within. Then you can either try to pop each section of the nodule on the fossil plane and glue the pieces together to form two halves or possibly glue the pieces together first and hope for a better split along the fossil plane on another freeze.

Patience always wins out over brute force (though brute force can be fun at times--though detrimental to your nodules). Many people have cycled nodules dozens or scores of times before getting one to pop. When it is a gloriously preserved fossil you feel vindicated for your steadfast patience, when it is a dud after all that time you feel let down. Helps to have lots of nodules to increase the odds of the former.

Good luck and post images of any interesting finds.

Cheers.

-Ken

[Rob Russell]

What Ken said. I might include letting the nodules dry out completely (perhaps outside in the sunlight) after your tenth cycle, or so. This will cause the nodule to shrink down to its smallest form. Which may entice a nodule to pop open after being swollen to its largest potential. I've had several nods pop this way. Good luck!

And after 30+ rounds of freezing and thawing with no results I'd let them dry completely, and then take a hammer to them. Gently at first, of course.

Edited July 2, 2015 by Rob Russell