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A few months ago I started to prepare this specimen which we collected five or so years ago near Wee Jasper, NSW. Specimens from this site must be acid prepared since they are encased in a hard limestone, making mechanical preparation impossible. Included will be my method for preparing this specimen, as well as my mistakes! Placoderm fossils from this site are typically found as black cross sections, just like the pictured specimen. Bone can be distinguished from other fossils in most cases due to the bumpy texture present on the exterior surface. To consolidate the specimen before working on it, I applied very dilute paraloid-b72 to the bone. At this stage, a dilute solution is best to ensure the paraloid can penetrate as deep into the bone as possible. If the ratio of paraloid to acetone is too high, the solution will be too viscous and the paraloid will only coat the surface of the bone. Next, I air scribed the bulk of the matrix I wanted to remove in order to greatly speed up the process. Here is the specimen after a couple of baths in 8% acetic acid (double strength store bought vinegar): Between acid baths, I let the specimen soak in water for a couple of days to remove any residual vinegar and prevent the build up of crystals which may form inside the bone and damage it once it dries out. Once dry, I applied more of the dilute paraloid to the freshly exposed bone with an eye dropper, making sure the bone was soaked and well consolidated. A photo showing matrix carefully removed with an air scribe between acid baths: I think it was around this point I made a very annoying and easily preventable mistake - I broke the fossil while moving it. It was easy to glue the pieces back on with a stronger, more viscous solution of 20% paraloid but now there are some ugly cracks through the specimen in places. I opted for paraloid instead of superglue because it is easily removable, if I'm not satisfied with my reattachment I just have to apply some acetone and the glue will dissolve again. I broke a couple of other pieces off too which is incredibly annoying, fragile fossils and I don't tend to mix well! Here are some photos of the finished specimen: Note the cracks on the right side of the specimen in this photo. I can't remember how I broke so much off at one time but it is incredibly annoying and so easily avoidable! The fracture towards the left side of the specimen here is natural, it may have been filled in by a band of silica which makes up much of the remaining rock. The crack in this photo was a natural fracture, but it looks like a larger chunk of bone fell off when I was gluing it back together before I started the acid preparation. This photo was taken at almost same angle as the "before" photo below it for reference! Here it is easy to see where the blueish limestone dissolved away, leaving only the bone and the bands of silica which make a convenient stand and support for the fossil. Thank you for reading:)
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Just started prepping this out and i have no clue what it is, it is surrounded by crinoid bits so i thought it was a stem but its just .. have a look anyway guys and see what you think
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What are the white things that look like bird droppings
Brian James Maguire posted a topic in Fossil ID
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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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trying to figure out if this is all one fossil or two separate ones
Brian James Maguire posted a topic in Fossil ID
hi guys, need some help again as to what is going on with this fossil, i had one part of it on here before and it was suggested it was a solitary coral but i prepped out some more of it today and to my surprise it looks like the new part i found is connected to the first, , both seem to have a spicule visible, as always your help would be greatly appreciated, i included a video as it is hard to get it all in photos as it is spiraled around the rock Video.mov- 2 replies
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hi guys, bit confused as to what these are, i found them on the beach yesterday, and preped them out today, any ideas ?
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Hello all. New user from central Maine. I found what I believe to be a fossil in the stream in my back yard. I used an app to identify the rock as limestone. Limestone is not native to my area, but there is a source in nothern Maine about 250km away. If it is limestone I would guess it was deposited during the last glaciation of the Laurentide ice sheet. It looks like a plant to me, a whole leaf maybe. The raised " stems" are hollow and there is the round ball ont the end. This round ball has two holes which is why i thought maybe a worm. These holes are tiny and symetrical, but only able to observe them with a jewelers loop. Thanks for any info.
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This one came to me without any information. My best guess is some kind of Ceraurus, from a Trenton Group (Simcoe Gp?) formation in Ontario. Can anyone fill in any more detail than that for me? I know it's rough and maybe not enough features to identify it. Is the bryozoan identifiable? Is the rock distinctive enough to say which formation it might be from? I'll get better pics later if needed.
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Hello! I’m Kate. I love rocks and i went rock hunting while on vacation in missouri. What i found was a ton of fossils. So many that i found myself trying to be selective…. I can only carry so much. i have very limited information on fossils so lets just say i know basically nothing. I dont buy them and have no plans to sell. so this is, to me, the most amazing fossil i found. Ive been working on cleaning away the rock for a couple of weeks but the central fossil was pretty much just ss you see it here. I only had to clear a little between what im calling the top and the bottom. Most of my cleaning has been on the right snd left sides of the rock. this was found in a dry creek bed in Hannibal Missouri. any assistance and advice is greatly appreciated. Im cleaning with vinegar, dental pick, scribe, straight pin, etc. kind regards, Kate
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I live in the mountains of Cibola County NM, lots of ancient volcanos. I was gathering limestone rocks for my rock wall I’m building and noticed this. I know fossils are pretty common in these rocks, it looks like the spiral of a snail or something. Anyone know what it is?
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I have some Devonian era fossils i'd like to clean up a bit, i was wondering about good tools or methods of removing limestone matrix without damaging delicate fossils
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I acquired these two slices of something from a rockhound couple in our club. They could not remember what they are or where they came from, but they could be from Arizona or somewhere in the Southwest US as they spend their winters in Arizona and always come back with stuff from collecting and wheeling and dealing down there. The bigger piece especially looks like oncolites to me, but I have been fooled before. Does anyone recognize either of these, and more importantly where they might be from? (If I can figure out the location I'll have a better chance of tracking down the ID/age.) Both pieces came already polished on one side. Smaller one has scratches. I tested both with vinegar and the larger one fizzes. (It would not fizz on the polished surface, but on the rough edge it did). The smaller one did not noticeably fizz. I thought it looked fossily but obviously different from the bigger one, so it might have been from a different chunk from the same site or it may be completely unrelated. Maybe not even sedimentary. The little 'bits' in the smaller piece seem to have crystalline interiors but surrounded in the same type of reddish 'buildup' that the oncolites(?) in the larger piece have. I'm not really expecting a decisive answer (I've not been too lucky in getting mystery items confidently ID'd lately, from the forum or otherwise... I seem to have a knack for digging up strange things). But I thought I would survey the forum in the off-chance someone recognizes the material. A Google image search did not turn up a perfect match for either. The color balance in my photos may be a bit off (indoor lighting), but it's the best I could do for now. I could try direct sunlight tomorrow. Side-by-side comparison of both pieces: Weathered edges (smaller piece on top) - the greyish patches could be either paint or rock saw sludge, it won't come off easily: