connorp Posted June 17, 2019 Share Posted June 17, 2019 I have a few nodules that haven't split from my Mazon Creek trip in early March. They have been through I'd guess 20-30 freeze-thaw cycles by now. I have been getting impatient, so I decided to whack them with a hammer and chisel. I've smacked each of them like a dozen times, but they still won't split. It's not obvious where the bedding plane (?) might lie, so I've struck them from all sides to no avail. Is this an indication that there is nothing inside, and therefore no bedding plane? Link to comment Share on other sites More sharing options...
Nimravis Posted June 17, 2019 Share Posted June 17, 2019 When I whack them I only use a hammer and no chisel. If they are still in good shape, continue the freeze / thaw method- it is the preferred way. There also is the great possibility that they do not contain anything, but I would still freeze them and leave them in for a longer period of time before thawing. Link to comment Share on other sites More sharing options...
connorp Posted June 17, 2019 Author Share Posted June 17, 2019 8 hours ago, Nimravis said: When I whack them I only use a hammer and no chisel. If they are still in good shape, continue the freeze / thaw method- it is the preferred way. There also is the great possibility that they do not contain anything, but I would still freeze them and leave them in for a longer period of time before thawing. I've been doing cycles of 2 days soaking, 2 days freezing. Should I up the freezing to 4 days or more? Link to comment Share on other sites More sharing options...
Nimravis Posted June 17, 2019 Share Posted June 17, 2019 Try leaving them in the freezer for +1 week. 1 Link to comment Share on other sites More sharing options...
Mark Kmiecik Posted June 17, 2019 Share Posted June 17, 2019 I usually kept on freezing and thawing for at least 50 cycles. The specimens that contain fauna I have found take more to crack open than flora. You also want to make sure that the concretions are completely saturated -- all the way to the center. To do this you must just soak them for at least a week to ten days before you freeze them. If there's no water in the middle to expand you can freeze/thaw until you turn blue and only the outside will begin to crack and peel off. As soon as the water freezes it has done it's job. One push per freeze is all you get. You may want to let them sit an extra day when thawed to take on extra water into the void created by freezing. Air is compressible and you want that void filled with water. Granted, we're talking about microns of gap, but it adds up. 4 Mark. Fossil hunting is easy -- they don't run away when you shoot at them! Link to comment Share on other sites More sharing options...
stats Posted June 18, 2019 Share Posted June 18, 2019 Drying them in the sun a few times after a freeze/thaw cycle can help. I have some that opened after a few years and many cycles. I don't always wait that long, but am more patient with a nearly perfect shape. Post some pictures. Are you sure they are concretions? A chunk of iron stone won't ever open. Cheers, Rich Link to comment Share on other sites More sharing options...
connorp Posted June 19, 2019 Author Share Posted June 19, 2019 On 6/17/2019 at 10:49 PM, stats said: Drying them in the sun a few times after a freeze/thaw cycle can help. I have some that opened after a few years and many cycles. I don't always wait that long, but am more patient with a nearly perfect shape. Post some pictures. Are you sure they are concretions? A chunk of iron stone won't ever open. Cheers, Rich Yeah I’m certain. I guess I just wasn’t letting them soak for nearly as long as I should have. Going to let them soak for 10 days now and cross my fingers. Link to comment Share on other sites More sharing options...
TheRocksWillShoutHisGlory Posted June 19, 2019 Share Posted June 19, 2019 I have also found that it works better to make sure they are only one layer when soaking, without other concretions laying on top of them. I have had a lot of problems with poor fracturing when I have all the concretions in the same bucket stacked on top of each other. 1 Link to comment Share on other sites More sharing options...
connorp Posted July 24, 2019 Author Share Posted July 24, 2019 Went back on Monday and got a nice load. As they're soaking, I'm wondering if I have been doing this wrong: when I freeze them, should I freeze them in water or dump the water out first? Or does it matter? Link to comment Share on other sites More sharing options...
gieserguy Posted July 24, 2019 Share Posted July 24, 2019 I always freeze in water, but there might be other methods! 1 Link to comment Share on other sites More sharing options...
Mark Kmiecik Posted July 24, 2019 Share Posted July 24, 2019 In water is the way I do it. Otherwise they begin to dry out. Most freezers nowadays are ventilated to prevent frost. This also tends to dry out the concretions if exposed. Even in a sealed container they tend to dry out unless absolutely airtight. Don't forget to soak them for at least a week before the first freeze/thaw. The water must penetrate all the way through or it does nothing but 'squeeze' them instead of expanding from the inside out. 2 Mark. Fossil hunting is easy -- they don't run away when you shoot at them! Link to comment Share on other sites More sharing options...
deutscheben Posted July 24, 2019 Share Posted July 24, 2019 Yes, I think they need to remain submerged, otherwise there is no way you will maintain the saturation needed for the process. I don't usually keep track of freeze/thaw cycles, but I know I have also had nodules I freeze-thawed for a few years without splitting. Hammering them has almost always been disappointing for me- I know @Nimravis is a master with the sledge and gets good results, but when I do it, it usually just results in pieces chipping off and eventually revealing nothing. 2 Link to comment Share on other sites More sharing options...
Mark Kmiecik Posted July 24, 2019 Share Posted July 24, 2019 3 hours ago, deutscheben said: I know @Nimravis is a master with the sledge and gets good results, but when I do it, it usually just results in pieces chipping off and eventually revealing nothing. It tends to work better when there's a fossil in the concretion. The ones that are really hard and very difficult to hammer open are usually duds. Duds don't have a weak plane within which a fossil lies. The reason fossil-bearing concretions split open is because the fossil itself prevents the material on the ventral side to bond as securely to the material on the dorsal side, thereby creating a weak plane between them. I'll firmly tap all the way around the edge several times after 50 cycles, and go full-blown psycho on them after 75. If you're using a freezer you can thaw with warm water or in the oven, let them sit out for a couple of hours and then back into the freezer. Thawed daily, it takes 2.5 months to reach 75 cycles. Of course, sometimes you can't or forget, so about 4 months is the longest you'll have to wait for results. Some concretions split after only one cycle. Some will split when tapped around the edge with a hammer without freezing them at home because they went through enough winter freeze and thaw cycles before you found them. Some are found already open for the same reason. Once you've done several thousand, you can pretty much know what will get the job done the best way as soon as you hold the fossil. Freeze/thaw still yields the best results with the least damage to the specimen, and that's why this method is preferred over others. The other thing that needs to mentioned is that when tapping the concretions after freeze/thaw the best results are obtained when the concretion is completely dry all the way through, which can be confusing because you want to keep them wet all the way through for each cycle. The key is to look for obvious cracks that follow the edge for at least one third of the concretions perimeter. No crack = back in the freezer. Crack = let dry and tap. If it doesn't open, soak again and continue freeze/thaw. When being tapped with a hammer, the concretion should be held in your hand (pad your palm with several layers of cloth), and not between the hammer and a hard spot like concrete or a brick. You are not trying to split it open as you would using a hammer and chisel, but merely trying to 'shock' the edge all the way around the fossil into failing. That's why you should tap all the way around the perimeter instead of repeated blows to the same spot. A hard surface opposite the blow can direct/reflect the force in a direction perpendicular to the weak plane and break the concretion across the specimen instead of along it. Tapping on either end of oval or long concretions can cause it to crack along the axis of the specimen but perpendicular to the plane in which it lies, so I recommend minimal tapping of the ends. I feel as if I'm giving away to many "trade secrets" here, but I hate the thought of potentially great specimens turning into garbage because of the need for instant gratification. Mazon Creek is for folks with the patience of saints, or those seeking Nirvana. Only after years of collecting and thousands and thousands of concretions will you begin to develop a 'feel' for the rock itself and the potential of the find. If you follow Nimravis's thread "Sometimes you gotta whack 'em" in the discussion topic you'll notice that he puts certain concretions aside to freeze/thaw instead of hammering them. He's probably opened 30,000 concretions or more. He knows the odds of something good being in it by the size, shape, color, grain, texture, thickness, and sound when tapped lightly with a hammer. There's no substitute for experience and with Mazon Creek material, experience is critical. EDIT: My apologies for getting carried away. I had my eye on where I was going as opposed to where I've been. 4 Mark. Fossil hunting is easy -- they don't run away when you shoot at them! Link to comment Share on other sites More sharing options...
Nimravis Posted July 25, 2019 Share Posted July 25, 2019 @Mark Kmiecik as always Mark, a great write up. You are correct about getting the feel of a certain concretion, I may grab a concretion and know 100 % that it will be a dud I still have to whack it- it just makes me feel better. Lol And yes, I have a few 5 gallon buckets with perfect concretions that I will just freeze over the winter and only tap if I see a slight crack. After I go through my remaining buckets that I will crack open, I will still have these other buckets to last me the next decade or so. 1 Link to comment Share on other sites More sharing options...
bigred97 Posted July 29, 2019 Share Posted July 29, 2019 I have a question about this - when I have a larger concretion that splits and is a dud, if one or both of the halves are large I have been continuing the freeze/thaw process. I will do that for a number of cycles and eventually they might split again, otherwise I take the hammer to them. I can't recall ever finding something this way. Am I wasting my time with this? If a concretion splits and is a dud, is there any chance it could still contain something in another plane? Perhaps I could stop the freeze/thaw cycles with these and just hammer the halves (which is a load of fun!). Link to comment Share on other sites More sharing options...
Randyw Posted July 29, 2019 Share Posted July 29, 2019 I’m not an expert in this but from what I’ve picked up in reading and posts there’s normally only one item per nodules and duds are empty. The concretion forms around a single nucleus (fossil or otherwise). Link to comment Share on other sites More sharing options...
Mark Kmiecik Posted July 29, 2019 Share Posted July 29, 2019 29 minutes ago, bigred97 said: I have a question about this - when I have a larger concretion that splits and is a dud, if one or both of the halves are large I have been continuing the freeze/thaw process. I will do that for a number of cycles and eventually they might split again, otherwise I take the hammer to them. I can't recall ever finding something this way. Am I wasting my time with this? If a concretion splits and is a dud, is there any chance it could still contain something in another plane? Perhaps I could stop the freeze/thaw cycles with these and just hammer the halves (which is a load of fun!). Each concretion is different. It really depends on how promising the shape, color, grain and thickness are. I have had a few (very few) that cracked in a different plane the second time around and revealed a decent specimen. Was it worth the time and effort? So far, no spectacular finds, but the next one could be a tully. There's no hard and fast rules. It's more of an art than a science. I usually treat it as potentially rare and valuable until it starts to frustrate me and then I just smack it with a hammer. 2 Mark. Fossil hunting is easy -- they don't run away when you shoot at them! Link to comment Share on other sites More sharing options...
Mark Kmiecik Posted July 29, 2019 Share Posted July 29, 2019 49 minutes ago, Randyw said: I’m not an expert in this but from what I’ve picked up in reading and posts there’s normally only one item per nodules and duds are empty. The concretion forms around a single nucleus (fossil or otherwise). If you look at Nimravis's thread "Sometimes you just have to whack them" in this same discussion topic you will see a few that have multiple fossils in different layers or even a second fossil on the surface of the concretion. Sometimes you find "twin" concretions, that have grown into each other. Some concretions are what is known as floor tile, similar to a crinoid hash plate, that is composed of forest floor debris which is often found through every layer of the concretion, solid all the way through. Sometimes there are multiple species in a concretion that are not in contact with each other, so concretions don't necessarily form around a single nucleus, although most of the time this is the case. With MC concretions just about anything you can imagine can and does happen. I have one or two that have two or three different species in distinctly different layers that have split open to reveal the fossil. The duds may actually have a very small fossil in them that just doesn't form a large enough "weak plane" so that the concretion splits in that plane no matter how carefully you try. Many of the duds show silvery "stains" that may have been some kind of organic matter but decomposed into an indistinguishable form. Not all the processes involved in the formation of these concretions are well-known at this point, and we may never know them exactly. The shape of the concretion very roughly follows the shape of the specimen, so sometimes you can make a very good guess of what is actually in it before it splits open. 2 Mark. Fossil hunting is easy -- they don't run away when you shoot at them! Link to comment Share on other sites More sharing options...
Nimravis Posted July 30, 2019 Share Posted July 30, 2019 8 hours ago, Mark Kmiecik said: have one or two that have two or three different species in distinctly different layers that have split open to reveal the fossil. @Randyw As Mark stated- and here are some examples: 2-clams at different ends of the concretion and 1 of them appears to be trying to escape entrapment. Here are a couple twin Essexella asherae , the first concretion has them on different planes. Here is another double- The next concretion has two different species- worm and a jellyfish. This last one has three different fossils- a fern, a seed and a jellyfish. 5 Link to comment Share on other sites More sharing options...
bigred97 Posted July 31, 2019 Share Posted July 31, 2019 Thanks everyone! Good to know I haven't been wasting my time, although I probably won't freeze/thaw most concretions that are already split for too many more cycles before I bring out the hammer. Nimravis - I love those examples! I haven't found any yet that have 2 different species - wow! I especially like the worm/jellyfish pairing, it's like they are posing for a selfie together. And three species in one concretion, special indeed. 2 Link to comment Share on other sites More sharing options...
stats Posted August 1, 2019 Share Posted August 1, 2019 On 7/29/2019 at 12:20 PM, bigred97 said: I have a question about this - when I have a larger concretion that splits and is a dud, if one or both of the halves are large I have been continuing the freeze/thaw process. I will do that for a number of cycles and eventually they might split again, otherwise I take the hammer to them. I can't recall ever finding something this way. Am I wasting my time with this? If a concretion splits and is a dud, is there any chance it could still contain something in another plane? Perhaps I could stop the freeze/thaw cycles with these and just hammer the halves (which is a load of fun!). For Mazon River concretions, I tend to leave things in for more cycles and try to split the multiple layers. The river concretions have many layers. I have found things, usually delicate ferns, when I keep trying. For all other localities, once I get a split, it's done. However, very uneven splits I leave in longer, unless the matrix doesn't seem like it will have something else. Cheers, Rich Link to comment Share on other sites More sharing options...
stats Posted August 1, 2019 Share Posted August 1, 2019 On 7/29/2019 at 12:37 PM, Randyw said: I’m not an expert in this but from what I’ve picked up in reading and posts there’s normally only one item per nodules and duds are empty. The concretion forms around a single nucleus (fossil or otherwise). From most localities, that is correct. I have found ferns from Pits 1 and 2 that have fern leaves on multiple layers. Mazon River concretions are different. They are very layered and I tend to keep them in to try and split all or most layers. Cheers, Rich 1 Link to comment Share on other sites More sharing options...
bigred97 Posted August 1, 2019 Share Posted August 1, 2019 That's a good point, Rich. I agree about the Mazon River concretions - they are very different than the ones I find in Pit 11 or Braceville. You can easily get many different layers to split off from each of the river ones. Many sort of peel off in layers. They also seem to have a much higher hit rate if you pick ones that aren't too large. I have almost no luck with the really big ones. 1 Link to comment Share on other sites More sharing options...
stats Posted August 2, 2019 Share Posted August 2, 2019 8 hours ago, bigred97 said: That's a good point, Rich. I agree about the Mazon River concretions - they are very different than the ones I find in Pit 11 or Braceville. You can easily get many different layers to split off from each of the river ones. Many sort of peel off in layers. They also seem to have a much higher hit rate if you pick ones that aren't too large. I have almost no luck with the really big ones. Yes, unfortunately it's hard to pass up the big ones. They look so inviting. I'm going to be more selective this year. I have been working through a bunch of blank big ones from last year. Cheers, Rich Link to comment Share on other sites More sharing options...
bigred97 Posted August 2, 2019 Share Posted August 2, 2019 If you ever find something that's eye-popping in a big one, let me know so I can go back to taking all of those again! haha It actually seems to me like it has something to do with thickness. If I found a big one that was sort of flat and long, I think I would still take that. But those big thick ones were just no good at all. 1 Link to comment Share on other sites More sharing options...
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