dpreynolds Posted January 17, 2020 Share Posted January 17, 2020 Although I am brand new here, I already have a question. Unfortunately, no photos yet, but I will describe the best I can. I see these things at Lake Pueblo on a regular basis. In the light grey sediment/shale, where i find seashell fossils, I also see small balls (3/4" or so) that look like iron. They have a color like rusted iron. Rough on the outside. Almost perfectly spherical. They discolor the rock that holds it (slightly) around the ball. I have not checked for magnetic characteristics. I cut one open and it seems to have a starburst type pattern on the inside. I heard somewhere that when hot metal (iron) is cooled quickly (possibly when this area was a sea), it may leave that pattern. I also wondered if they are round because they were molten and hit the water, cooled quickly, and sank to the bottom, to the sediment. Does anyone have a general idea of what they may be? I have my uneducated theories...So, if anyone can shed light, it's been driving me nuts. Thanks! Link to comment Share on other sites More sharing options...
Rockwood Posted January 17, 2020 Share Posted January 17, 2020 Iron rich concretion. 2 Link to comment Share on other sites More sharing options...
caldigger Posted January 17, 2020 Share Posted January 17, 2020 They sound like something similar to Moqui Marbles or close relative iron concretions. 4 Link to comment Share on other sites More sharing options...
fossilnut Posted January 17, 2020 Share Posted January 17, 2020 (edited) @caldiggerWhat an aggregation of Moqui marbles! I thought you might find one here and there but not in this abundance. Is this common? Where is this general area where the picture was taken? @dpreynoldsWhat you describe as a star burst pattern I believe I have seen in marcasite nodules. Usually a hole at the center and the pattern I believe are crystalline marcasite. Others will know more. Welcome to the forum a lot of people with more knowledge than me. Edited January 17, 2020 by fossilnut added welcome and picture 1 Link to comment Share on other sites More sharing options...
fossilnut Posted January 17, 2020 Share Posted January 17, 2020 (edited) Does not look like picture came through. Will try again Cockscomb marcasite Edited January 18, 2020 by fossilnut got picture to show Link to comment Share on other sites More sharing options...
dpreynolds Posted January 17, 2020 Author Share Posted January 17, 2020 @caldigger that photo looks pretty much exact except for the one that's broken. The inside is different. I haven't found any grouped like that. Just singles in the shape. I'll be back down there and get photos and post them, probably sunday. So what creates them at the level of the shells? Also, thanks @fossilnut and @Rockwood! Link to comment Share on other sites More sharing options...
caldigger Posted January 17, 2020 Share Posted January 17, 2020 That picture is from a deposit in Utah. Link to comment Share on other sites More sharing options...
Mark Kmiecik Posted January 18, 2020 Share Posted January 18, 2020 2 hours ago, dpreynolds said: @caldigger that photo looks pretty much exact except for the one that's broken. The inside is different. I haven't found any grouped like that. Just singles in the shape. I'll be back down there and get photos and post them, probably sunday. So what creates them at the level of the shells? Also, thanks @fossilnut and @Rockwood! Google Moqui Marbles -- there's a ton of photos and info online. Some locations in Utah have DRAMATIC amounts in a small area. There's some info on how they formed also. The size seems to range from pea to baseball. 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...
Rockwood Posted January 18, 2020 Share Posted January 18, 2020 Ping pong ball sized examples are fairly common in Maine. Link to comment Share on other sites More sharing options...
grandpa Posted January 18, 2020 Share Posted January 18, 2020 Sounds a lot like the pyrite/marcasite/limonite nodules found in cretaceous fossiliferous limestone formations in Austin, Tx. Of course this is a guess based on no photo references. And, oh yes, if I haven't said so earlier, welcome to TFF from Austin. Link to comment Share on other sites More sharing options...
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