alej9582 Posted April 19, 2017 Share Posted April 19, 2017 Hi all, Originally I thought this was an iron concretion, I still believe it is but was wondering is there is any geologist in the group (or expert) who can point out a more specific type of mineral (siderite? hematite?). Never seen a concretion like this and it was intermingled with Shale packed with plant material and root casts. I want to know if there is any correlation to this mineral and abundance of fossils in the deposits I'm frequenting. Found in Triassic deposit Deep River Formation, NC (Newark Super Group). Regards to all, Alex Link to comment Share on other sites More sharing options...
Rockwood Posted April 19, 2017 Share Posted April 19, 2017 I am familiar with a cretaceous site where concretions with plant material in them can fairly reliably be spotted by their unique appearance. I don't know the minerals involved or how common it is though. 1 Link to comment Share on other sites More sharing options...
alej9582 Posted April 19, 2017 Author Share Posted April 19, 2017 Thank you @Rockwood Even though the site is quite older all concretions I gathered have barely visible plant imprints (blueish black) on the outside shell. The "coal color" seems to have a direct relation to a coal deposit positioned directly bellow the shale (Cumnock Formation) where this concretions are found. This deposits are well know for some of the best Triassic Plant fossils in the eastern US so your comment makes a lot of sense. Before I cracked this open I thought I would find some plant material inside considering the coalified imprints outside but the nucleus of the concretion looks iron related. Once again thank you! Alex Link to comment Share on other sites More sharing options...
Plax Posted April 20, 2017 Share Posted April 20, 2017 can we get a sharper close up of the broken end? Some of the highly mineralized triassic bone from NC has this look in general. Probably just a concretion as you surmise but wanting to rule out a very worn bone fragment. 1 Link to comment Share on other sites More sharing options...
alej9582 Posted April 20, 2017 Author Share Posted April 20, 2017 @plax, I will take a picture this afternoon with a Nikon instead of my phone. Will post it then. Regards, Alex Link to comment Share on other sites More sharing options...
ynot Posted April 20, 2017 Share Posted April 20, 2017 To answer the original question,,,, The elements that make an iron concretion can be from organic or geologic origins. All living things have the minerals needed in them. A iron concretion can be made of several iron minerals but is typically limonite (geologic term for rust). Siderite, pyrite and marcasite will usually have a metallic appearance to them. They may have been altered to hematite, goethite or magnetite but that is not common and would make them black or dark gray. (I have never seen a concretion that I would identify as these minerals.) The color of the streak is the easiest way to deturmane the makeup of a iron concretion, but is not very reliable. To be absolutely sure You would have to get a spectral analysis done. If it looks like rust I would just call it limonite. 2 Darwin said: " Man sprang from monkeys." Will Rogers said: " Some of them didn't spring far enough." My Fossil collection - My Mineral collection My favorite thread on TFF. Link to comment Share on other sites More sharing options...
alej9582 Posted April 20, 2017 Author Share Posted April 20, 2017 Than you Ynot! Link to comment Share on other sites More sharing options...
ynot Posted April 20, 2017 Share Posted April 20, 2017 1 minute ago, alej9582 said: Than you Ynot! You are welcome. Tony 1 Darwin said: " Man sprang from monkeys." Will Rogers said: " Some of them didn't spring far enough." My Fossil collection - My Mineral collection My favorite thread on TFF. Link to comment Share on other sites More sharing options...
EMP Posted April 20, 2017 Share Posted April 20, 2017 22 hours ago, alej9582 said: Hi all, Originally I thought this was an iron concretion, I still believe it is but was wondering is there is any geologist in the group (or expert) who can point out a more specific type of mineral (siderite? hematite?). Never seen a concretion like this and it was intermingled with Shale packed with plant material and root casts. I want to know if there is any correlation to this mineral and abundance of fossils in the deposits I'm frequenting. Found in Triassic deposit Deep River Formation, NC (Newark Super Group). Regards to all, Alex Does it dissolve or react with vinegar? If so, then it's likely siderite (iron carbonate). Otherwise I'd say hematite (Fe2O3) is most likely. Pyrite (iron sulfide) could also form concretions, however from what I gather the rock of the Newark Group were deposited on land and have their color due to the oxidation of iron in the rock/mud. 1 Link to comment Share on other sites More sharing options...
alej9582 Posted April 20, 2017 Author Share Posted April 20, 2017 Will test. Link to comment Share on other sites More sharing options...
EMP Posted April 20, 2017 Share Posted April 20, 2017 Make sure to only use a small chip from it and not the whole thing ! Link to comment Share on other sites More sharing options...
alej9582 Posted April 20, 2017 Author Share Posted April 20, 2017 Lol my wife wont like me using all her vinegar! Will use a few drops on a chip. Thank you @EMP Link to comment Share on other sites More sharing options...
Plax Posted April 20, 2017 Share Posted April 20, 2017 Newark sediments are river and lake deposits for the most part. The state museum in Raleigh has been doing research on the vertebrate fauna for quite some time. Link to comment Share on other sites More sharing options...
alej9582 Posted April 21, 2017 Author Share Posted April 21, 2017 @Plax That is correct. On the few years I have been visiting (and trying to find) outcrops I have read a lot about research both from NC Raleigh and from Appalachian. The Pekin formation here has produced great specimens of Rutiodon carolinensis, various types of Aetosaur among other reptiles and the Cumnock has yield many fishes and primitive mammals (Triassic all). Still this information on the Southern Tip of the Newark Super Group (Broadly named Deep River Formation) is less studied than most other deposits. What's very interesting is that most species found here are also found on the Chinele Formation of Arizona and viceversa as they are contemporaneous. I use the information of this highly studied formation to gather extra info. Paleontologist in NC are also very helpful and responsive but most of them can get into quarries and private lands where we have no access to. On another note, I meant to tell you guys that the outer shell of the inner shell (if that makes sense) of the concretion is phosphorite. Link to comment Share on other sites More sharing options...
EMP Posted April 21, 2017 Share Posted April 21, 2017 13 minutes ago, alej9582 said: @Plax That is correct. On the few years I have been visiting (and trying to find) outcrops I have read a lot about research both from NC Raleigh and from Appalachian. The Pekin formation here has produced great specimens of Rutiodon carolinensis, various types of Aetosaur among other reptiles and the Cumnock has yield many fishes and primitive mammals (Triassic all). Still this information on the Southern Tip of the Newark Super Group (Broadly named Deep River Formation) is less studied than most other deposits. What's very interesting is that most species found here are also found on the Chinele Formation of Arizona and viceversa as they are contemporaneous. I use the information of this highly studied formation to gather extra info. Paleontologist in NC are also very helpful and responsive but most of them can get into quarries and private lands where we have no access to. On another note, I meant to tell you guys that the outer shell of the inner shell (if that makes sense) of the concretion is phosphorite. So it's a phosphate (or phosphorus oxide) mineral. Looking at the depositional history of most phosphorites: "Phosphates are known to be deposited in a wide range of depositional environments. Normally phosphates are deposited in very shallow, near shore marine or low energy environments. This includes environments such as supratidal zones, littoral or intertidal zones, and most importantly estuarine.[8] Currently, areas of oceanic upwelling cause the formation of phosphates. This is because of the constant stream of phosphate brought from the large, deep ocean reservoir (see below). This cycle allows continuous growth of organisms.[6] Supratidal zones: Supratidal environments are part of the tidal flat system where the presence of strong wave activity is non-existent. Tidal flat systems are created along open coasts and relatively low wave energy environments. They can also develop on high energy coasts behind barrier islands where they are sheltered from the high energy wave action. Within the tidal flat system, the supratidal zone lies in a very high tide level. However, it can be flooded by extreme tides and cut across by tidal channels. This is also subaerially exposed, but is flooded twice a month by spring tides.[9] Littoral environments/ intertidal zones: Intertidal zones are also part of the tidal flat system. The intertidal zone is located within the mean high and low tide levels. It is subject to tidal shifts, which means that it is subaerially exposed once or twice a day. However, it is not exposed long enough to withhold vegetation. The zone contains both suspension sedimentation and bed load.[9] Estuarine environments: Estuarine environments, or estuaries, are located at the lower parts of rivers that flow into the open sea. Since they are in the seaward section of the drowned valley system they receive sediment from both marine and fluvial sources. These contain facies that are affected by tide and wave fluvial processes. An estuary is considered to stretch from the landward limit of tidal facies to the seaward limit of coastal facies. Phosphorites are often deposited in fjords within estuarine environments. These are estuaries with shallow sill constrictions. During Holocene sea-level rise, fjord estuaries formed by drowning of glacially-eroded U-shaped valleys.[9] The most common occurrence of phosphorites is related to strong marine upwelling of sediments. Upwelling is caused by deep water currents that are brought up to coastal surfaces where a large deposition of phosphorites may occur. This type of environment is the main reason why phosphorites are commonly associated with silica and chert. Estuaries are also known as a phosphorus “trap”. This is because coastal estuaries contain a high productivity of phosphorus from marsh grass and benthic alge which allow an equilibrium exchange between living and dead organisms." https://en.wikipedia.org/wiki/Phosphorite I'd say that considering these environments an iron oxide is most likely. Even if the original mineral were pyrite, it's possible that it was weathered and eventually oxidized itself into something like Fe2O3. Edit: This is because the water in riverine or estuarine environments are prone to contain dissolved molecules and elements that would over time work with the mechanical breakdown of mineral grains and oxidize a mineral's elements and react to form oxide compounds. In this case it's iron and oxygen. This is why hulls on boats and ships must have a special coating (often zinc) on their steel parts to help prevent corrosion brought on by the oxidation of the iron component, which would weaken the structure of the ship. It's also why the military stores a lot of it's old equipment in deserts (though there are other reasons for that as well, some not having to do anything with chemistry or geology...). Another edit: I'd definitely take a whack at that rock. Phosphorite is known to form in rocks because the phosphate component was leached out of bone material. 1 Link to comment Share on other sites More sharing options...
alej9582 Posted April 21, 2017 Author Share Posted April 21, 2017 @EMP My mind went to ocean as soon as I was told about it (opinion from a college dude without deposition information) which made it close to imposible BUT the Pekin formation from some reason (in the Ponoma Quary terrestial and lacustrine 220M ago) has a small quantity phosphate presence. My original opinion as well as your original and last comment makes more scene though. Link to comment Share on other sites More sharing options...
EMP Posted April 21, 2017 Share Posted April 21, 2017 Did you catch my latest edit? There might be some bone fragments if phosphorus compounds are involved. Link to comment Share on other sites More sharing options...
alej9582 Posted April 21, 2017 Author Share Posted April 21, 2017 Just saw it. The thing is so weird from the outside and inside. I have found many concretions in the area but the shoe shape of this thing is a new one for me. I have a few other funky shaped concretions I collected along with this one last weekend, one of them has no particular shape and weights 20 pounds, I guess I will have a fun weekend even without fossils. I will try to break it without to much damage and let you know. Appreciate the replies. Alex Link to comment Share on other sites More sharing options...
westcoast Posted April 21, 2017 Share Posted April 21, 2017 Just curious but how was the determination of phosphorite made? Also it is worth commenting on an earlier comment above about siderite reacting with vinegar. Siderite actually responds very poorly with acid and it is not a reliable field test. Link to comment Share on other sites More sharing options...
alej9582 Posted April 22, 2017 Author Share Posted April 22, 2017 The vinegar test failed. Te conclusion based only on visuall analysis (photo) without depositional info whatsoever. I took out all layers I could before smaking it open which I'll do tonight. There are two "cores" within it. They are a perfect match when puten together. Photos in a minute. Sorry for any errors im walking while writing. Alex Link to comment Share on other sites More sharing options...
alej9582 Posted April 22, 2017 Author Share Posted April 22, 2017 Here are some pics. Link to comment Share on other sites More sharing options...
alej9582 Posted April 22, 2017 Author Share Posted April 22, 2017 Link to comment Share on other sites More sharing options...
alej9582 Posted April 22, 2017 Author Share Posted April 22, 2017 This one is an invert so you can see the relief on the white spots. Link to comment Share on other sites More sharing options...
Plax Posted April 24, 2017 Share Posted April 24, 2017 I took some of the pattern to be haversian channels but probably not now. Bone can of course be tumbled into rounded elongate shapes and then enclosed in concretion later. The Newark Supergroup is all rift valley lake and river deposits. The North Atlantic was the result of this rifting which broke up Pangea. Link to comment Share on other sites More sharing options...
doushantuo Posted April 24, 2017 Share Posted April 24, 2017 and probabably will remain forever ignorant Link to comment Share on other sites More sharing options...
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