Concretions and Artificial Weathering?

[Therandomkind]

Hello. I was just curious about what some good techniques for artificially weathering a concretion to get them open are? I've read that the best way to go is to soak, freeze, thaw, and repeat. But none of the sources I've read describes how long that takes. I'm sure it varies from specimen to specimen but is this process weeks, months or years? Does anyone have any other methods or resources about the process? I was thinking of giving it a try and could use some more information on the process. It seems kind of like the old geode gamble in a way. There's no way of knowing what's inside unless it's partially exposed already. I don't have a geologist's hammer and I think I'd feel bad if I cracked one by hitting it too hard or at the wrong angle. Are there any other tools that are recommended?

[RuMert]

45 minutes ago, Therandomkind said:

is this process weeks, months or years?

It depends on the layer and  preservation. They wait for months with Mazon Creek but with my previous set of concretions (different layer) heating on stove/ freezing in freezer for a short time worked fine. With some Cretaceous ammonite concretions (usually very tough) it was enough to put them in fire and then a body of water right in the field

[Therandomkind]

3 minutes ago, RuMert said:

It depends on the layer and  preservation. They wait for months with Mazon Creek but with my previous set of concretions (different layer) heating on stove/ freezing in freezer for a short time worked fine. With some Cretaceous ammonite concretions (usually very tough) it was enough to put them in fire and then a body of water right in the field

Wow! How cool. Thanks for sharing. Do you have any pictures by chance?

 

[RuMert]

I didn't think of taking pictures, sorry:)

[Therandomkind]

It's okay. Thanks anyways.

 

[Fossildude19]

Be careful with the heat and cool strategy. 

Out of the oven and into water can be explosive in the results. 

Often you end up with shards of broken rock rather than a fossil. 

The Freeze/Thaw method is tried and true. There is a reason so many people use this method. It may take longer, but the results are much better. 

Some folks leave buckets of concretions filled with water out in the winter weather all season, then check them in the spring for signs of cracking. 

Some concretions just have outer layers peel away. Others have no fossils at all. 

Basically, you can do freeze thaw for 48 hours each pass. 24 hours is doable, but I think it would be better to let the water really seep in. 

 

You can also use a hammer, but, in my experience, this is usually not as good as Freeze thaw - the concretions don't always split nicely with the hammer. 

[Mark Kmiecik]

Soak 4-5 inch concretions for 10 days. Small ones up to 2 inch for 5 days. Anything over 7 inch 15 days, over 10 inch 20+? days. You want the water to soak ALL THE WAY through. Freeze until you're sure it's frozen all the way through. Thaw until you're sure it's thawed all the way through. Either of those two steps can be anywhere from four hours to four days, depending on the size, density and porosity of the minerals forming the concretion. A slow freeze + a slow thaw decreases the possibility of the concretion shattering into dozens of small fragments. The term "haste makes waste" applies directly to this method as well as dealing with fossils in general. 

 

Search this forum for 'Mazon Creek' and 'freeze thaw' for additional info. Don't expect too much from most concretions. Only those from specific (usually well-known) locations will contain fossils, but any concretion is worth a shot. Good Luck.