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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.

Hi, I know it’s not a fossil but can anybody help with ID’ing this rock which I think is an agate? thanks! IMG_3464.mov

Hi there. Can someone let me know what they think this is. I was near San Bernardino county and found this. I can’t tell what it is. Heavier than normal rocks( similar to geode weight) very odd to me. Really stood out. Has a slight bit of banding on the top edge but it is truly beautiful

Can someone help me figure out if these are spores on an agate?

Absolutely giant agate found in untouched land in Minnesota. Hundreds more lie in the creeks in rivers.

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

I'm new to this forum. Does anyone know what this rock is? The middle looks quartz, and at the edge is blue. When held to the light or sunlight the blue turns to an amber color. Any help appreciated!

Found this on the beach in Delaware. Skimming Google and the closest I could come to was fire agate. Anyone have a better identification? Thanks!

Wondering what type of rock this is? Not a whale rock 😂 😂

Thanks for any help! Love this forum!

Just wanting to see if this is an egg. A few said no but then I cracked it open. Thank you

Wanting to ask if anyone knows what this is? Thank you

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

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.

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

A friend found this on the north shore of new orleans in landscaping rocks , she want to know if its a fossil

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.

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?

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?

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!

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.

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.

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