jamesp
Cave Dweller 
Member since October 2012
Posts: 36,662
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Post by jamesp on Feb 26, 2019 3:08:14 GMT -5
Yes, agricultural lime is crushed limestone or chalk and thus is calcium carbonate. I use common lime with a lot of my experiments. It is calcined limestone forming calcium oxide primarily used to make cement, but also in the processing of some foods like hominy. If you have a USB microscope it would be cool to see the silica crystals under high magnification. That may also help tell you if they are from diatoms or not. Other possibility is silica replacement of the coral polyps when live can still be very sharp. There could be something else preset that cold be buffering acids such as maybe phosphate buffers or something else. The gas build up would just be something to keep in mind since water pH varies from place to place and even the rocks can alter pH or the lichens that grow on a lot of them. The tannic water that cuts thru the limestone bedrock dissolves river channels 10 to 20 feet deep in the limestone leaving behind exposed shoals of silicifications James. Most of the source of the tannic acid for say the Suwannee River is the massive Okeefenokee Swamp serving as a steamy rotting organic acid machine. The tannic acid is strong enough to make the water quite drinkable since only a few types of bacteria and protozoans can survive in it. Guessing the chemical reactions are more involved than just the effect of the tannic acid on the clay, soil and limestone. The silicifications in this coral are without a doubt the linear 'pipeline' structures along the walls and centers of the polyp structures. Partial silicifications are more the norm than the exception. Yes, they are sharp (and inflict pain) like live polyps.  And these partial silicifications vary in quantity from shoal to shoal exposure as moving down the river. This particular shoal is made of almost 100% poorly silicified corals, the shoal above and below this one has some of the most solid silicifications. Basically sections of sandy river banks yield poor silicifications and sections of the river with clay banks yield solid and more colorful silicifications. Perhaps the clay held moisture longer for the dissolved silica to form and replace.  |
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jamesp
Cave Dweller
Member since October 2012
Posts: 36,662
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Post by jamesp on Feb 26, 2019 3:54:24 GMT -5
Hey grumpybill, jamesp, and others - I was taught a slightly different angle regarding the silica dangers that helped me choose (or not) to use PPE. I was taught that the recommended protections for things like silica, asbestos, and mercury are seemingly out of proportion to the danger because once these items get into our body they literally never get out. The result is that every exposure, no matter how small, is cumulative over an entire lifetime. We can't possibly quantify the actual "dose received" due to the many circumstances of exposure you guys already mentioned. And there's no way to know what future exposures may be (i.e., a 9/11 type event, earthquake, moving onto a gravel road, etc). So the prudent course is to eliminate the known or predictable exposures. That context sometimes helps me choose to stop and put on a mask when I really would rather continue without one. And sometimes I'm willing to take my chances and don't. I'm only sharing this because I was helped by the information & thought I'd pass it along. I'm all about freedom to make personal choices.  Best to wear a mask kskid in any dusty environment. A mask designed for the particulate matter in the air if possible. Or proper ventilation to prevent inhaling. Especially in our younger years. And certainly if doing highly physical activity in a dusty environment. A fan when welding to divert smoke from being inhaled for instance. Certainly this coal miner has enough sense to wear a mask  |
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Post by vegasjames on Feb 26, 2019 6:07:33 GMT -5
Yes, agricultural lime is crushed limestone or chalk and thus is calcium carbonate. I use common lime with a lot of my experiments. It is calcined limestone forming calcium oxide primarily used to make cement, but also in the processing of some foods like hominy. If you have a USB microscope it would be cool to see the silica crystals under high magnification. That may also help tell you if they are from diatoms or not. Other possibility is silica replacement of the coral polyps when live can still be very sharp. There could be something else preset that cold be buffering acids such as maybe phosphate buffers or something else. The gas build up would just be something to keep in mind since water pH varies from place to place and even the rocks can alter pH or the lichens that grow on a lot of them. The tannic water that cuts thru the limestone bedrock dissolves river channels 10 to 20 feet deep in the limestone leaving behind exposed shoals of silicifications James. Most of the source of the tannic acid for say the Suwannee River is the massive Okeefenokee Swamp serving as a steamy rotting organic acid machine. The tannic acid is strong enough to make the water quite drinkable since only a few types of bacteria and protozoans can survive in it. Guessing the chemical reactions are more involved than just the effect of the tannic acid on the clay, soil and limestone. The silicifications in this coral are without a doubt the linear 'pipeline' structures along the walls and centers of the polyp structures. Partial silicifications are more the norm than the exception. Yes, they are sharp (and inflict pain) like live polyps. And these partial silicifications vary in quantity from shoal to shoal exposure as moving down the river. This particular shoal is made of almost 100% poorly silicified corals, the shoal above and below this one has some of the most solid silicifications. Basically sections of sandy river banks yield poor silicifications and sections of the river with clay banks yield solid and more colorful silicifications. Perhaps the clay held moisture longer for the dissolved silica to form and replace. Beautiful place. Would be fun to explore.
But the explanation makes no sense. Tannic acid will not eat away at the calcium carbonate. Tannic acid reacts with calcium carbonate forming insoluble calcium tannate.
Most likely the channels were made primarily by carbonic acid, which is well known for this also forming many caverns in limestone. Carbon dioxide dissolves in water forming carbonic acid. This reacts with the calcium carbonate (limestone, coral, dolomite, calcite, etc.) forming calcium bicarbonate, which is extremely water soluble and thus can be easily washed away.
Other acids are commonly formed by the dissolving of atmospheric gases in to water. Especially nitrogenous and sulfurous gases forming the corresponding nitrogenous and sulfurous acids such as nitric acid and sulfuric acids. These acids not only react with the calcium carbonate forming very soluble salts but during their reaction with the calcium carbonate also yield carbon dioxide and water thus forming carbonic acid as well.
As for the silicification there are going to be a couple of factors involved here.
First if pH. It has been demonstrated that a slightly acidic pH on silica sources can increase the level of soluble silica (silicic acid) by up to 100 times. Therefore the acidity would increase the level of soluble silica for silicification.
Second would be the fact that calcium has a high affinity for silica, which is why we see so many previous calcium sources, such as bones and shells, silicified. The whole process of course is more involved but the basics are the silica actually serves initially as a nucleator for the formation of calcium carbonate crystals. Calcium carbonate though also attracts silica forming silica gels and even quartz. Eventually the calcium can be replaced and thus in this case agatized coral.
The role of the organic acids from leaves and barks for example is the increased formation of silicic acid.
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Post by parfive on Feb 26, 2019 13:39:25 GMT -5
Certainly this coal miner has enough sense to wear a mask Northam, is that you? |
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Post by vegasjames on Feb 26, 2019 18:37:41 GMT -5
Certainly this coal miner has enough sense to wear a mask Northam, is that you? I am surprised that nobody has thrown a fit over this guy appearing in black face. I guess he will never be able to run for office now. |
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Post by grumpybill on Feb 26, 2019 19:27:14 GMT -5
I am surprised that nobody has thrown a fit over this guy appearing in black face. I guess he will never be able to run for office now. I've thought about running for local office. But I'm afraid someone will find out my parents took me to a black-face Minstrel Show when I was 5. |
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jamesp
Cave Dweller
Member since October 2012
Posts: 36,662
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Post by jamesp on Mar 3, 2019 6:47:44 GMT -5
The tannic water that cuts thru the limestone bedrock dissolves river channels 10 to 20 feet deep in the limestone leaving behind exposed shoals of silicifications James. Most of the source of the tannic acid for say the Suwannee River is the massive Okeefenokee Swamp serving as a steamy rotting organic acid machine. The tannic acid is strong enough to make the water quite drinkable since only a few types of bacteria and protozoans can survive in it. Guessing the chemical reactions are more involved than just the effect of the tannic acid on the clay, soil and limestone. The silicifications in this coral are without a doubt the linear 'pipeline' structures along the walls and centers of the polyp structures. Partial silicifications are more the norm than the exception. Yes, they are sharp (and inflict pain) like live polyps. And these partial silicifications vary in quantity from shoal to shoal exposure as moving down the river. This particular shoal is made of almost 100% poorly silicified corals, the shoal above and below this one has some of the most solid silicifications. Basically sections of sandy river banks yield poor silicifications and sections of the river with clay banks yield solid and more colorful silicifications. Perhaps the clay held moisture longer for the dissolved silica to form and replace. Beautiful place. Would be fun to explore. But the explanation makes no sense. Tannic acid will not eat away at the calcium carbonate. Tannic acid reacts with calcium carbonate forming insoluble calcium tannate. Most likely the channels were made primarily by carbonic acid, which is well known for this also forming many caverns in limestone. Carbon dioxide dissolves in water forming carbonic acid. This reacts with the calcium carbonate (limestone, coral, dolomite, calcite, etc.) forming calcium bicarbonate, which is extremely water soluble and thus can be easily washed away. Other acids are commonly formed by the dissolving of atmospheric gases in to water. Especially nitrogenous and sulfurous gases forming the corresponding nitrogenous and sulfurous acids such as nitric acid and sulfuric acids. These acids not only react with the calcium carbonate forming very soluble salts but during their reaction with the calcium carbonate also yield carbon dioxide and water thus forming carbonic acid as well. As for the silicification there are going to be a couple of factors involved here.
First if pH. It has been demonstrated that a slightly acidic pH on silica sources can increase the level of soluble silica (silicic acid) by up to 100 times. Therefore the acidity would increase the level of soluble silica for silicification.
Second would be the fact that calcium has a high affinity for silica, which is why we see so many previous calcium sources, such as bones and shells, silicified. The whole process of course is more involved but the basics are the silica actually serves initially as a nucleator for the formation of calcium carbonate crystals. Calcium carbonate though also attracts silica forming silica gels and even quartz. Eventually the calcium can be replaced and thus in this case agatized coral.
The role of the organic acids from leaves and barks for example is the increased formation of silicic acid.
Thanks for these explanations James. The chemistry is more complicated than imagined but to far from being understandable. Sure is a lot more inorganic compounds involved than fist expected. As mentioned in the other thread the carbonic acid seems to be a dominate force. On the subject of silicification. I find many hollow coral pseudomorphs with broken silicified polyp tubes that have silicified over AFTER breakage. Keep in mind the 'tubes' are normally silicified parallel to each other. It is interesting that the tubes got glued together with silica after they were broken and littered the cavity randomly. Curious as to what forces could have broken the internal tubes during silicification and exactly how recent/fast the silicification is occurring. Is silicification occurring today ? check out these pseudomorphs showing breakage:   Not broken, typical:   |
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Post by vegasjames on Mar 3, 2019 19:33:09 GMT -5
The breakage could have been from fish running in to the corals or foraging around the corals for food.
Since the silicification process involves an exchange reaction with the calcium I doubt the process is continuing since the calcium should have all been replaced by now.
That last one in the pics is exceptionally nice.
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jamesp
Cave Dweller
Member since October 2012
Posts: 36,662
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Post by jamesp on Mar 4, 2019 8:17:44 GMT -5
The breakage could have been from fish running in to the corals or foraging around the corals for food. Since the silicification process involves an exchange reaction with the calcium I doubt the process is continuing since the calcium should have all been replaced by now. That last one in the pics is exceptionally nice. The 'stalactites' are similar to cave formations but not caused by drip formation but more so by coating/replacing parallel (or broken) tube structure. Funny you mention fish. I had made trips for years to this shallow river and noticed freaky large reflections in late summer in the deeper pools. And too deep to see the river bottom. Guessing they were alligator gar. One fine August day I was minding my business sitting on a shoal collecting botryoidal fragments in the gravel and out of the lower pool bursts out a like 7 foot fish going up the shoal next to me. The giant fish was on his side in this shallow shoal and slapping his tail propelling himself making a big racket not but a few feet from me. Bout messed myself. Come to find out sturgeon make their way up these rivers. Not figuring they would come up such a small tributary where I was. They travel 150 miles up the Suwannee River from the Gulf of Mexico, then turn north on this Withlacochee tributary way up into Georgia another 80 miles. I had seen signs posted 120 miles south on the Suwannee warning jet skis to lower speed due to sturgeon getting frightened and jumping in front of the jet ski and seriously injuring the operator. Check out this article: "Woman hit by flying fish on her PWC A P A sturgeon jumped out of a river and hit a woman riding a personal watercraft. It's the latest such injury involving the flying fish along the Suwannee River. Officials say Sharon Touchton of St. Petersburg had serious injuries, but she was later discharged from a hospital after the accident. Wildlife authorities say Touchton had been camping near the town of Suwannee in north Florida. No one saw the collision when she was on the watercraft, so it's not exactly clear what happened. But once she was able to talk, Touchton simply said something about a “big fish.†Officials say last year ten people were injured in accidents caused by the jumping fish. Sturgeon are large, prehistoric-looking fish with hard plates along their backs that can grow up to eight feet long and up to 200 pounds. Researchers still aren't sure why the large fish jump." |
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