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I’ve been interested in biogenic influences on minerals for a while. I have a large collection of stromatolites/oncolites/microbial mats etc. where algae influenced the minerals. I also have hot spring and cave minerals that were also influenced by biogenic processes. However, a new book, shown below has opened up a whole new class of Biominerals mostly influenced by nano bacteria. A lot of the theories in this book are at the forefront of science and are not yet mainstream or even accepted in some cases. However, I thought it was definitely worth a few posts here on TFF. Marco Campos-Venuti 2022 Biominerals microbial life in Agates and other Minerals (526 pages): I’ll start with some biogenic influence examples in agate. The below figure is from the book. Note although the figure talks about agate, a lot of the examples are really in jasper and not agate. Campos-Venuti goes into detail about the processes that lead to these geometries but I don’t want to get too wonky for this post. Below are a few specimens from my collection which demonstrate each of the five geometries of bacteria colonies from the figure. My friend who told me about this book warned me that if I bought the book, I would most likely be buying a lot more, different specimens. He was definitely right. 1. Laminated (truthfully I find this the hardest of the geometries to really distinguish in a piece) I have a number of pieces of Lavic Siding Jasper. Pictures of one are shown below (Note I still have to sand and polish this piece.) You can see a brecciated laminated structure. : Lavic Siding Jasper slab, Mojave Desert, California (186 grams 5.75x4x.25 inches) 2. Dendritic (Dendrites are really easy to see in minerals, although not all dendrites are from biogenic influences) I have lots of dendritic examples in minerals. A lot of dendrites are not biogenically influenced but the result of crystallization. So to be sure, I’m using a specific type of material that is from an area that Campos-Venuti specially uses as an example in his book. Sonora Dendritic Jasper slab, Mexico (136 grams 4.125x3x.31 inches). 3. Lumpy or reniform Campos-Venuti hasn’t really identified many examples of this geometry. I have two different pieces of King Cobra Jasper from India shown below. King Cobra Jasper Slab India (180 grams 7x3.25 inches 7mm thick): King Cobra Orbicular Jasper Slab, India (208 grams 4.5x4.75 inches x5.7mm): 4. Flame There are a lot of really nice examples of biogenic flame influences. Below are two difference pieces from Mexico. Flame Agate end cut, Mexico (335 grams 4X2X2 inches): Flame Agate Slab, Chihuahua, Mexico (668 grams 5.75x2.25x2.625 inches): 5. Plume There are a lot of really nice examples of biogenic plume influences. Below are two different small pieces from Oregon. NorthRidge Plume Agate Slab, Owyhee Mountains, near Homedale, Eastern Oregon (27 grams 2.25x1.5x.125 inches): NorthRidge Plume Agate Slab, Owyhee Mountains, near Homedale, Eastern Oregon (22 grams 2.25x1.45x.125 inches) I hope this post may have increased both an understanding of biominerals, biogenically influenced minerals, and an interest in them. Marco Sr.
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Howdy, I was wondering if anybody could tell me what they think about these rare coral fossils that I find on the Oregon Coast. They are agatized and take a nice polish. Thank You
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Hi all! We found this fossil a few days ago on a trip to Charmouth, UK. I’m brand new to fossil prep and I thought I give this a go. However this one confuses me a little because I’m not sure what is the best approach. Should I try to clean it up on the agatized side or the other side? Any advice would be greatly appreciated! TIA 72800635334__1DF8B1D0-465D-4CCE-821F-00D60C850061.MOV
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Hello I’m new here just wanted to see if someone could help me identify this round agate as I feel it’s an egg.
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Found this coral head today where I’ve found other agatized coral in the Tampa Bay area in FL. To me it looks suspicious, it has a slightly blue color around its edges and has some botryoidal formations on the outside. It’s not super lightweight though, so I don’t think it’s hollow (or completely hollow). Does this look like it’s worth cutting? Is it likely to have any voids or botryoidal formations inside based on other agatized corals you guys have seen? recorded-478291984396.mp4
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Hi there I inherited some what I believe to be bones maybe of the dinosaur variety? They take a nice polish. I believe these are from somewhere in the US but I have no idea where they are from or what geologic age.
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Found what appears to be petrified wood in the tampa bay area on a beach. I’ve never found petrified wood in FL before so I’m just posting to make sure this is what it is. It looks exactly like wood, before I picked it up I thought it was just driftwood. But when I picked it up i immediately knew it was stone, it is heavy and clanks on other stones. Is it petrified palm wood maybe?
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Hi everyone, Recently found this oyster shell specimen from an area near Tampa FL amongst dredged limestone where I’ve found agatized coral. 99% sure it’s fossilized (has a very small amount of limestone stuck to the bottom), but something interesting is that there appears to be botryoidal agate coating it. Is this an agatized oyster? Is this a common find around tampa? And can I bleach it to remove algae?
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Hello!! Any insight on this would be appreciated! My daughter found it today diving in the ocean. We are in south Florida. It’s roughly 4inchesx3inches and 303g (0.668lbs) thanks!
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Hello! I’m new to the forum and come across fossils and interesting rocks regularly. I would love to learn more about my findings from anyone here that has a keen interest in helping someone like me expand my knowledge! These photos are of my most recent finding, but I don’t know what it is/ where it’s from/ when I dates back to.
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I own this silver-mounted snuffbox, made in England circa 1740. Is the lid made of petrified wood, or simply regular agate? The metal portions are silver, with the interior fire-gilt (a highly toxic process that involved mercury vapors!). Thanks in advance for your expert help.
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Agatized dinosaur egg from India recognized in museum collection
Oxytropidoceras posted a topic in Fossil News
Sparkly Rock in Museum Turns Out to Be 60-Million-Year-Old Dinosaur Egg In a remarkable find, a lustrous mineral formed inside a fossilized titanosaur egg. Gizmodo, Natural History Museum of London The first known dinosaur egg? A new discovery from the Museum's collection Josh Davis, Natural History Museum of London. Yours, Paul H. -
Any idea what this is? I found it in AZ, Desert area, Sandstone, Agate and Quartz around, but no others like this. It's about 5" across. IMG_20230322_153126.heif IMG_20230322_153144_HDR.heif
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Is this agate petrified wood? Most beautiful ones I have ever found. Color of honey and dark colored crystals are translucent Found in college station Texas in creek. Brazos river valley area. The watershed valley is loaded with p wood. I lightly sanded bottom and top of first rock in pic. many mineral experts please let me know if this is any rare due to size or what it is etc ? thanks bryan.
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I was surprised to learn that turritellia(elimia) agate comes from the Green River fm. It seems surprising that such radically different matrices are present in the same formation. Does anyone know the association, are there clumps of agate mixed in with green river fish/leaves/etc or are they isolated deposits that got lumped in together due to similar age and location? *edit*: Also, Eden valley wood/algae and giant stromatolites. Truly a diverse formation
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the one closest to I carved to look like an eyeball. Im sorry for including this. four of these,eye included , are the same creature? Hello from SE Arizona.
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Need help confirming what I found. This speciman was found in Milwaukee, WI. I found it in some loose landscape rock around the building I work in. Unfortunately I don't have a ruler on me right now but it's about 2 inches long and 3/4 inches wide. Originally I thought it was agate but someone in my rock group on Facebook says it looks to be silicified stromatoporoid. After doing a Google search I came across stromatolites also. So I'm not sure which one it could be. It's a beautiful specimen. What looks to be quartz on the bottom and what I originally thought was agate surrounding it. Any ideas of what this could be? Thanks a ton! (Sorry about holding the speciman. These pics were taken when I found it and I have the specimen at home and not on me right now. I tried to crop out my fingers) Pics: side view, end view and top view
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There are cross hatch patterns in the wood making it almost look woven. The rock imbedded in it or attached to it looks like amber. its bright yellow and dark when no light is behind it. The amber or agate looks like it has some of the same fiber pattern around the edges.