pleecan Posted December 17, 2009 Share Posted December 17, 2009 As water freezes, phase transition result in volume expansions... the frozen water can act like a wedge and split the rock. The is the same effect as weather in places that cycle below freezing at night and warms above freezing in the day time.. This is a tricky technique...Has any one tried soaking a fossil in water then freezing it in the freezer to help remove fossil matrix.... tell us your experience on this fringe technique... what are the pros and cons.... your thoughts are welcome... curious technique. PL Link to comment Share on other sites More sharing options...
Auspex Posted December 17, 2009 Share Posted December 17, 2009 That is a standard practice for Mazon Creek nodules, except that they are immersed in a pan and the whole shebang is put through as many freeze-thaw cycles as it takes to pop them. "There has been an alarming increase in the number of things I know nothing about." - Ashleigh Ellwood Brilliant “Try to learn something about everything and everything about something.” - Thomas Henry Huxley >Paleontology is an evolving science. >May your wonders never cease! Link to comment Share on other sites More sharing options...
pleecan Posted December 17, 2009 Author Share Posted December 17, 2009 (edited) That is a standard practice for Mazon Creek nodules, except that they are immersed in a pan and the whole shebang is put through as many freeze-thaw cycles as it takes to pop them. Thanks Auspex for that information... I did not know that... always thought that they said a prayer and simply hit the Mazon Creek nodules with a hammer and if you got lucky the split with be down the middle revealing perfect cleavage of both halves of the fossil... I could see than this way of freezing is a whole lot more control... as the nodules will be under lots of compression ... crack will develop along natural fault lines= bedding plane of cleavage. PL Edited December 17, 2009 by pleecan Link to comment Share on other sites More sharing options...
Auspex Posted December 17, 2009 Share Posted December 17, 2009 A small supplication is called for before employing either technique "There has been an alarming increase in the number of things I know nothing about." - Ashleigh Ellwood Brilliant “Try to learn something about everything and everything about something.” - Thomas Henry Huxley >Paleontology is an evolving science. >May your wonders never cease! Link to comment Share on other sites More sharing options...
Mike Owens Posted December 17, 2009 Share Posted December 17, 2009 Good plan, except when your specimen has hidden hair-line fractures. -----"Your Texas Connection!"------ Fossils: Windows to the past Link to comment Share on other sites More sharing options...
pleecan Posted December 17, 2009 Author Share Posted December 17, 2009 Good plan, except when your specimen has hidden hair-line fractures. Can't hurt by saying a prayer and have some devine favour on your side. ...good point Mike PL Link to comment Share on other sites More sharing options...
Ron E. Posted December 17, 2009 Share Posted December 17, 2009 We have nodules from the Fayetteville Shale formation here in NW Arkansas that simply won't split in half, too irregular. So you freeze/thaw until they basically shatter, and if you're lucky you end up with a fairly complete Cravenoceras fayettevillae or two from the crumbles. Link to comment Share on other sites More sharing options...
pleecan Posted December 18, 2009 Author Share Posted December 18, 2009 We have nodules from the Fayetteville Shale formation here in NW Arkansas that simply won't split in half, too irregular. So you freeze/thaw until they basically shatter, and if you're lucky you end up with a fairly complete Cravenoceras fayettevillae or two from the crumbles. Thanks Ron for your reply! PL Link to comment Share on other sites More sharing options...
Nicholas Posted December 18, 2009 Share Posted December 18, 2009 I do it with some coal material with variable success, it seems to be effective at taking the coal off of the fossil but it takes a lot of time and many many cycles. Some just don't seem to work, others are impressive. Link to comment Share on other sites More sharing options...
pleecan Posted December 18, 2009 Author Share Posted December 18, 2009 I do it with some coal material with variable success, it seems to be effective at taking the coal off of the fossil but it takes a lot of time and many many cycles. Some just don't seem to work, others are impressive. Thank you Nicholas, for your reply... looks like a bit of luck can't hurt with this particular method... PL Link to comment Share on other sites More sharing options...
Nicholas Posted December 18, 2009 Share Posted December 18, 2009 Thank you Nicholas, for your reply... looks like a bit of luck can't hurt with this particular method... PL Luck and patience. I would suggest fully sub merging the area of the fossil which you want to "crack". Seems to help, but it is hard to control what gets wet. Link to comment Share on other sites More sharing options...
pleecan Posted December 18, 2009 Author Share Posted December 18, 2009 (edited) Luck and patience. I would suggest fully sub merging the area of the fossil which you want to "crack". Seems to help, but it is hard to control what gets wet. I like to think out loud... to control the degree of wetting... This is a far out idea if on the assumption the rock is porous and we want to control the cleavage plane.... if one were to cover the area that you do not wish to wet with a hydrocarbon ie melted wax .... sort of a masking technique then submerge the hold thing in water .... the waxed cover parts will repel water... non wetting, hydrophobic.... followed by freeze cycle...this could control the cleavage plane to some degree.... just a thought. PL Edited December 18, 2009 by pleecan Link to comment Share on other sites More sharing options...
DDD Posted December 18, 2009 Share Posted December 18, 2009 Interesting, pleecan. Might be worth an experiment or two. I suspect that with a very porous matrix it won't matter what you mask off or not - water may well soak through the entire body of the nodule anyway, but that's not meant to pour cold water on your idea (heh ). A thought I had was what effect would accelerating/accentuating the freeze/thaw cycle by using liquid nitrogen to fast freeze the nodule, followed by a warm oven to warm through (repeat as necessary) have? Might be worth sacrificing a nodule to experiment with to see what happens... Dan Link to comment Share on other sites More sharing options...
Auspex Posted December 18, 2009 Share Posted December 18, 2009 Generally better, I think, to apply patience; slow and easy. Extreme thermal shock might be too robust for some materials. Natural (ie: slow) freeze-thaw cycles might tend to favor splitting on the natural plane of weakness. Wouldn't want to wind up with fossiliferous aquarium gravel. "There has been an alarming increase in the number of things I know nothing about." - Ashleigh Ellwood Brilliant “Try to learn something about everything and everything about something.” - Thomas Henry Huxley >Paleontology is an evolving science. >May your wonders never cease! Link to comment Share on other sites More sharing options...
pleecan Posted December 18, 2009 Author Share Posted December 18, 2009 Interesting, pleecan. Might be worth an experiment or two. I suspect that with a very porous matrix it won't matter what you mask off or not - water may well soak through the entire body of the nodule anyway, but that's not meant to pour cold water on your idea (heh ). A thought I had was what effect would accelerating/accentuating the freeze/thaw cycle by using liquid nitrogen to fast freeze the nodule, followed by a warm oven to warm through (repeat as necessary) have? Might be worth sacrificing a nodule to experiment with to see what happens... Dan Thanks for the reply Dan... Similar effect (presumed) can be had with dry ice frozen CO2 rather than liquid N2.... The only consideration is that the stress gradient generated is proportional to the rates of cooling or heating ... meaning if the stress is too great in a short time interval... the nodule could shattered rather than a control clean cleavage... It is always fun kicking ideas around... thought experiments are always free. PL Link to comment Share on other sites More sharing options...
pleecan Posted December 18, 2009 Author Share Posted December 18, 2009 Generally better, I think, to apply patience; slow and easy. Extreme thermal shock might be too robust for some materials. Natural (ie: slow) freeze-thaw cycles might tend to favor splitting on the natural plane of weakness. Wouldn't want to wind up with fossiliferous aquarium gravel. I agree with you Auspex.... as observed in nature.... a gradual heating and cooling rates are best to achieve a controlled cleavage. PL Link to comment Share on other sites More sharing options...
DDD Posted December 18, 2009 Share Posted December 18, 2009 Yes, that all makes sense... Dan Link to comment Share on other sites More sharing options...
pleecan Posted December 19, 2009 Author Share Posted December 19, 2009 (edited) With the cooler weather ... I took a walk to the backyard and examine old scarp rock which was dumped and weathered into piles yrs ago... a prime example of freeze thaw action... a newly split rock.... revealed a beautiful cystoid from Verulum/Bobcaygen Formation Carden Quarry, Brechin ON.... a very nice Christmas present considering Carden Quarry is now closed to collectors.... PL Edited December 19, 2009 by pleecan Link to comment Share on other sites More sharing options...
Bear Posted December 19, 2009 Share Posted December 19, 2009 The Ojibwa used heat/freeze to free up copper in their UP mines. It worked well enough for them. Link to comment Share on other sites More sharing options...
glacialerratic Posted December 19, 2009 Share Posted December 19, 2009 I've got many nodules still in need of splitting. Sometimes it takes a long time. I was just about to give up on a nodule after 24+ cycles and wailing on it with a hammer, when it finally popped after a freezing -- a really nice flying insect. I've found that hitting a nodule hard with a hammer isn't the best idea. A few firm taps, and then back into water. Even with a nice fossil in a nodule, that splitting plane doesn't always cooperate the way you'd think it would. I *think* I'm currently working on a shark egg case, as a tip of the nodule split off revealing a little bit. Since the tip came off, it's been around 12 cycles, and some tiny cracks are just starting to show on the plane. I'm not sure if it will split cleanly or not, and a hammer just chips away at the edge. That siderite is hard stuff. On a side note, as a gravel pit hunter, I'll hit big boulders several times, trying to get a crack, and then go back after the winter to see if the weather opened things up a bit. One boulder got hit many times in '93 to no avail. I went back in '99 and scored 3 really nice cephs. The day before the snow started up here, I was making the rounds with my sledge, putting some nice cracks in some hard rocks I've had my eye on. I'm looking forward to next spring! Link to comment Share on other sites More sharing options...
RJB Posted December 19, 2009 Share Posted December 19, 2009 I dont know about the concretions you folks get over there, but the ones on the west coast seem to me to be unphased by that technique. One guy in Oregon swore by it. He said it worked 100% of the time. On the old California forum he gave me advice that I did not ask for and then demanded that I give him my crab sites. I will let you imagine how that went? HA!!! Another guy in Oregon said that the freeze thaw did not work for him but said that the 'freeze, then put into microwave' worked sometimes. He quite using that techneque after he destroyed his microwave. He also caught his microwave on fire too. And yet another fellow from washington tried all that stuff and came to the conclusion that if youve got a concretion where you cannot tell there is a crab in it, to start whacking it gently, then progressivly harder until it pops. That was the guy who founded NARG, a very smart fellow. RB Link to comment Share on other sites More sharing options...
Auspex Posted December 19, 2009 Share Posted December 19, 2009 The day before the snow started up here, I was making the rounds with my sledge, putting some nice cracks in some hard rocks I've had my eye on. I'm looking forward to next spring! Johnny Fossilseed! "There has been an alarming increase in the number of things I know nothing about." - Ashleigh Ellwood Brilliant “Try to learn something about everything and everything about something.” - Thomas Henry Huxley >Paleontology is an evolving science. >May your wonders never cease! Link to comment Share on other sites More sharing options...
Terry Dactyll Posted December 21, 2009 Share Posted December 21, 2009 I just wack em with a hammer and use a lump hammer underneath as an anvil.... the fossil inside creates a plain of weakness... and the open..... its worth noting to gradually increase the strength of your taps, as some almost fall open as the fossil takes up a large area of the nodule... Cheers Steve... And Welcome if your a New Member... Link to comment Share on other sites More sharing options...
Roz Posted January 8, 2010 Share Posted January 8, 2010 I have tried the microwave idea myself but the matrix exploded so couldn't tell if anything had been inside. I did nuke it too long. I may experiment with maybe 5 seconds at a time just as an experiment.... I am not suggesting this as a method. I will be using just clumps of matrix. Welcome to the forum! Link to comment Share on other sites More sharing options...
pleecan Posted January 8, 2010 Author Share Posted January 8, 2010 I just bought a few dozen of un open Mazon Creek nodules and will just place them in a pail of water on the patio and go through a series of freeze thaw cycles..... gentle approach I have got all winter for this project... bit like watching paint dry . PL Link to comment Share on other sites More sharing options...
Recommended Posts
Create an account or sign in to comment
You need to be a member in order to leave a comment
Create an account
Sign up for a new account in our community. It's easy!
Register a new accountSign in
Already have an account? Sign in here.
Sign In Now