DPS Ammonite Posted January 21, 2020 Share Posted January 21, 2020 I went back to my very productive Devonian Martin Formation and Mississippian Escabrosa Formation near Superior, Arizona to retrieve my large single crinoid head fossil. Amazing Arizona Adventure original post link After some acid prep four crinoids and one blastoid were clustered together. Currents probably sorted them by size and shape. Several more hours of acid prep made the remaining four best ones stand out. I had to carefully break away pieces of shell that adhered and covered the crinoids and blastoid. Careful monitoring of their progress prevented any of them falling off the matrix. The resulting piece is probably the finest crinoid and blastoid assemblage ever found in Arizona. Finding one crinoid or blastoid cast in Arizona is very hard let alone four or five together. The two largest crinoids in the center and left are likely Physetocrinus lobatus. The upper right is an Orophocrinus saltensis blastoid. The lower right is an unknown crinoid. (Any idea what it is?) The field of view is about 7.5 cm wide. Keep looking for updates as I prep and post more fossils. I found several loose crinoid heads. 13 My goal is to leave no stone or fossil unturned. See my Arizona Paleontology Guide link The best single resource for Arizona paleontology anywhere. Link to comment Share on other sites More sharing options...
doushantuo Posted January 21, 2020 Share Posted January 21, 2020 nice work,D Link to comment Share on other sites More sharing options...
Manticocerasman Posted January 21, 2020 Share Posted January 21, 2020 nice, what kind of acid do you use on them? growing old is mandatory but growing up is optional. Link to comment Share on other sites More sharing options...
DPS Ammonite Posted January 21, 2020 Author Share Posted January 21, 2020 2 minutes ago, Manticocerasman said: nice, what kind of acid do you use on them? Muriatic AKA HCl acid. The people at the hardware store must think that I have a really large pool with all the acid that I buy from them. 2 My goal is to leave no stone or fossil unturned. See my Arizona Paleontology Guide link The best single resource for Arizona paleontology anywhere. Link to comment Share on other sites More sharing options...
doushantuo Posted January 21, 2020 Share Posted January 21, 2020 be careful with the acid don't drop it Link to comment Share on other sites More sharing options...
DPS Ammonite Posted January 21, 2020 Author Share Posted January 21, 2020 3 minutes ago, doushantuo said: be careful with the acid don't drop it I never drop it. When I spill it I always have lots of water nearby to dilute it. My goal is to leave no stone or fossil unturned. See my Arizona Paleontology Guide link The best single resource for Arizona paleontology anywhere. Link to comment Share on other sites More sharing options...
Ludwigia Posted January 21, 2020 Share Posted January 21, 2020 Congrats on that unique find. Are the fossils silicified? Greetings from the Lake of Constance. Roger http://www.steinkern.de/ Link to comment Share on other sites More sharing options...
Ruger9a Posted January 21, 2020 Share Posted January 21, 2020 Awesome find and fantastic prep work. Do you neutralize the Muriatic acid on the fossil with a liquid solution of baking soda and then rinse thoroughly or just rinse? Link to comment Share on other sites More sharing options...
Monica Posted January 21, 2020 Share Posted January 21, 2020 What exquisite echinoderms!!! Congratulations on the awesome find and well done on the prep! Link to comment Share on other sites More sharing options...
DPS Ammonite Posted January 21, 2020 Author Share Posted January 21, 2020 1 hour ago, Ludwigia said: Congrats on that unique find. Are the fossils silicified? Yes. 1 hour ago, Ruger9a said: Awesome find and fantastic prep work. Do you neutralize the Muriatic acid on the fossil with a liquid solution of baking soda and then rinse thoroughly or just rinse? I just soak in fresh water for a period at least twice as long as it was in the acid changing the water a couple of times. Often the acid solution has been neutralized by the limestone when I take the fossil out. Soaking in water gets rid of the salt, calcium chloride. Insufficient soaking produces fossils that grow lots of needle like crystals. 3 My goal is to leave no stone or fossil unturned. See my Arizona Paleontology Guide link The best single resource for Arizona paleontology anywhere. Link to comment Share on other sites More sharing options...
Ruger9a Posted January 21, 2020 Share Posted January 21, 2020 35 minutes ago, DPS Ammonite said: Yes. I just soak in fresh water for a period at least twice as long as it was in the acid changing the water a couple of times. Often the acid solution has been neutralized by the limestone when I take the fossil out. Soaking in water gets rid of the salt, calcium chloride. Insufficient soaking produces fossils that grow lots of needle like crystals. Thanks! Link to comment Share on other sites More sharing options...
FossilDAWG Posted January 21, 2020 Share Posted January 21, 2020 How much do you dilute the acid? HCL is pretty harsh compared to acetic or formic acid, unless it is diluted a lot. Don Link to comment Share on other sites More sharing options...
Shamalama Posted January 21, 2020 Share Posted January 21, 2020 Very cool looking Crinoids. Some of the detail is very nice too. -Dave __________________________________________________ Geologists on the whole are inconsistent drivers. When a roadcut presents itself, they tend to lurch and weave. To them, the roadcut is a portal, a fragment of a regional story, a proscenium arch that leads their imaginations into the earth and through the surrounding terrain. - John McPheeIf I'm going to drive safely, I can't do geology. - John McPheeCheck out my Blog for more fossils I've found: http://viewsofthemahantango.blogspot.com/ Link to comment Share on other sites More sharing options...
DPS Ammonite Posted January 21, 2020 Author Share Posted January 21, 2020 7 minutes ago, FossilDAWG said: How much do you dilute the acid? HCL is pretty harsh compared to acetic or formic acid, unless it is diluted a lot. Don Starting with a 29% solution, I dilute it to a 10-20% solution. If the fossil is fragile, I use a lower concentration of acid to prevent concussion fracturing from the bubbles forming and popping. The biggest problem with the higher concentration solutions is from overtopping the container from the vigorous bubbles and organic slime from the limestone. 2 My goal is to leave no stone or fossil unturned. See my Arizona Paleontology Guide link The best single resource for Arizona paleontology anywhere. Link to comment Share on other sites More sharing options...
Fossildude19 Posted January 21, 2020 Share Posted January 21, 2020 Very nice prep work and awesome find, John! Thanks for posting it! Tim - VETERAN SHALE SPLITTER VFOTM --- APRIL - 2015 __________________________________________________ "In every walk with nature one receives far more than he seeks." John Muir ~ ~ ~ ~ ><))))( *> About Me Link to comment Share on other sites More sharing options...
Peat Burns Posted January 22, 2020 Share Posted January 22, 2020 Link to comment Share on other sites More sharing options...
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