How Many Different Ways Can A Fossil Become Mineralized?

[Mediospirifer]

On February 2nd, the Finger Lakes Mineral Club will be having an open house event at the Museum of the Earth in Ithaca, NY. We're in the planning stages now, and I'm working on assembling the displays I want to bring.

One of those will be about different mineralizations that fossils show. At present, I have a number of limestone, shale, and sandstone fossils to choose from, including a few brachiopods that appear to have the original material preserved, plus a few examples of types that are less common and possibly unknown to the general public:

-- Opalized shells from Australia

-- Petrified wood replaced with jasper

-- Agatized coral

-- A beetle from the La Brea tar pits

-- A piece of Lepidodendron from Pennsylvania coal

-- Shells from Florida that appear unaltered, including original color patterns on a few

-- Insects in amber

-- Green River fish fossils

Does anyone have any suggestions for other types that I should include information about? I'm planning on typing up some placards to put with my pieces explaining (as best I can) how these mineralizations occur.

If anyone has any information that I should include, I welcome the input!

Last year, we had 70+ visitors come by to check out our displays. We'll see how many visitors we get this year!

[mikecable]

I'll throw one or more echinoids from the Walnut Clay that have partial calcite replacement into the box you have coming. They also have some mild yellow fluorescence under an LED black light. Also some Straparolus sp? from the Finis Shale at Lake Jacksboro that are pyritized.

[mikecable]

Much more recent, and not always technically fossils, but dessication/mummification, freezing/freeze-drying, and adipocere/saponification.

[Mediospirifer]

I knew I was forgetting something! I shoud have included my pyritized brachiopod in my list.

Much more recent, and not always technically fossils, but dessication/mummification, freezing/freeze-drying, and adipocere/saponification.

I've heard of dessication/mummification and freezing/freeze-drying (also peat bog preservation), but adipocere/saponification is a new one for me. Research time!

Thanks!

[mikecable]

Igneous/volcanic--think Pompeii.

[mikecable]

I knew I was forgetting something! I shoud have included my pyritized brachiopod in my list.

I've heard of dessication/mummification and freezing/freeze-drying (also peat bog preservation), but adipocere/saponification is a new one for me. Research time!

Thanks!

I think peat bog preservation may be a form of saponification.

[Auspex]

I have always been amazed at the preservation and taphonomy at the Messel pit. LINK

[Mediospirifer]

Igneous/volcanic--think Pompeii.

Ah, yes. I have a few pieces of volcanic tuff in my rock collection, I could certainly display one as an example of what the matrix would look like. Thanks again!

I should probably also include my dinosaur gastrolith and some coprolites for the show.

[Mediospirifer]

I have always been amazed at the preservation and taphonomy at the Messel pit. LINK

That looks very interesting! I'll have to read more, and perhaps find some pictures that I can use.

[mikecable]

Ah, yes. I have a few pieces of volcanic tuff in my rock collection, I could certainly display one as an example of what the matrix would look like. Thanks again!

I should probably also include my dinosaur gastrolith and some coprolites for the show.

Research Hinds Cave coprolites. They collected more than 5000 dessicated human coprolites at Hinds Cave in the lower Pecos Valley in Texas (I believe around 5000 years old) and gained huge insights into the diet of Paleo/Archaic Native Americans. Kids love coprolites. I've been known to lick them in front of my students when they don't yet know for sure what they are. I tell them that mosasaur coprolites always taste like fish.

[mikecable]

Trace fossils.

[mikecable]

The Finger Lakes are one of the few places where saponification has taken place in recent forensic pathology investigations. Human bodies almost alway decompose, bloat, and float. Unless you sink them to the bottom of a cold, anaerobic lake like one of the Finger Lakes. I've got a somewhat morbid imagination.

[Mediospirifer]

Research Hinds Cave coprolites. They collected more than 5000 dessicated human coprolites at Hinds Cave in the lower Pecos Valley in Texas (I believe around 5000 years old) and gained huge insights into the diet of Paleo/Archaic Native Americans. Kids love coprolites. I've been known to lick them in front of my students when they don't yet know for sure what they are. I tell them that mosasaur coprolites always taste like fish.

I've been known to show coprolites to kids, putting the rock in the kid's hand and then telling them "that's a piece of dinosaur poop!" The reactions are amusing....I haven't tried tasting them, though!

The Finger Lakes are one of the few places where saponification has taken place in recent forensic pathology investigations. Human bodies almost alway decompose, bloat, and float. Unless you sink them to the bottom of a cold, anaerobic lake like one of the Finger Lakes. I've got a somewhat morbid imagination.

Interesting! I knew that Lake Superior was deep and cold enough to preserve bodies, and that the Finger Lakes are also deep and cold, but never thought about them being capable of preserving bodies.

I also have a somewhat morbid imagination, and a very earthy sense of humor!

[RichW9090]

Peat bog preservation is a form of tanning, rather than of saponification. The naturally occurring tannins in the watery environment produce leather.

Rich

[Wrangellian]

Seems like shells replaced by silica would be a basic 'must'. Check out http://en.wikipedia.org/wiki/Petrifaction for ideas..

What is fish material usually replaced with? I understand that phosphatic material like fish and brachiopods tend to preserve differently than regular calcite/aragonite shells even in the same deposit (I have noticed around here the brachiopods are a silvery material, flaky and impossible to extract intact, and occur in the same deposits as white shells that hold together fine, and in other places fish bits preserve blue where the regular shells are brown or black.)

[painshill]

You might like to point out that the word "fossil" is also arbritarily used to refer to items that are more than around 10,000 years old but not necessarily mineralized. Teeth and bones for example. I also saw a wooden fence post in a museum in Australia that was probably not much more than 100 years old which had effectively "fossilized" by mineralisation. In salt-marsh areas here in the UK you can also find pieces of WWII ordnance that have converted to siderite concretions in a kind of "fossilization" process.

As for insects in amber, don't neglect that the amber itself is also a fossil. You might also put up a sample of copal to demonstrate the difference. The mineral jet is also a fossil of course.

Trace fossils definitely. Think footprints, trilobite resting burrows, worm borings etc.

And don't forget stromatolites... interesting also because they may represent the earliest life forms in the fossil record.

[addition]: and don't forget fossil fuels too... coal, oil and (sometimes) peat.

Edited January 12, 2014 by painshill

[mikeymig]

I have some mammoth hair around here somewhere that's a neat fossil to show the public. A friend of mine lives in Africa and he has a fossil horse jaw that is partially replaced by turquoise. That's just something you might want to add to the discussion and if I can find the photo i will post it for you. Someone mentioned that some fossils fluoresce and if you have a UV light that would make them go wow. Oreodon teeth and other Oligocene mammal teeth from the American Badlands will "glow" orange under UV rays.

Mikey

Edited January 12, 2014 by mikeymig

[Mediospirifer]

Lots of good suggestions here! Thanks, everyone!

Amber, coal and stromatolites I had thought of, oil not so much. Peat I hadn't really thought of as fossil material, but yes, I can see that it could be.

Mikeymig, I would love to see a photo of that horse jaw!!! I'd never heard of turquoise as a replaement mineral before--agate, jasper, chert, flint, chalcedony, opal, and pyrite, yes, but not turquoise. Is that in the jasper family of minerals? I may have to do some more research!

I have some fluorescent fossils, including an oreodont jaw, unfortunately, the room where we're doing the open house event is too brightly-lit to show them effectively. Maybe by next year I'll have a dark-box for fluorescent displays.

I do have some Peace River Pleistocene fossils (deer bones, horse teeth, a partial mammoth tooth, plus others presently unidentified), does anyone know offhand what the minerology is there? Obviously, they're not completely mineralized, but some of the bones feel heavier in my hand than I'd expect for unaltered bone.

Something else I'll include (if I can locate it!) is a piece of tiger iron (made into a pendant, so not in with the rest of the rock collection). I've had it for years because it's a cool-looking rock. A month ago I found it mentioned in a book about jaspers, as an example of the Banded Iron Formations (also known as Red Beds), laid down during the original atmosperic oxygenation event! I've wanted a piece of Red Bed since I first heard about them, and it turns out I've had a piece all along! The original trace fossil?

Thanks for the help, folks!

Edited January 12, 2014 by Mediospirifer

[Scylla]

Speaking of iron, what about siderite nodules with iron oxide deposition preserving the fossil? Some of these started as pyritized and oxydized.

[BobWill]

You might consider replacing the word "mineralization" with the more general term "preservation" since mineralization and permineralization are just two of the forms of fossilization. You could also add "recrystallization", "bioimmuration" and "casts and molds". You could also divide your list into general categories with their different forms listed. Maybe someone with better knowledge about these distinctions could help with this. In case you have trouble finding information on bioimmuration, I believe it is when a shell like an oyster grows up against another stationary creature (dead or alive) and preserves an impression of it on the oyster shell. I'm not sure if this would fall under the general category of a trace fossil or a mold.

[Mediospirifer]

Speaking of iron, what about siderite nodules with iron oxide deposition preserving the fossil? Some of these started as pyritized and oxydized.

Looking up siderite nodules, I found the Mazon Creek deposits. Are these what you're thinking of?

If so, cool! I have a couple that would be neat additions to this display. I didn't know there was anything other than shale involved in the concretion!

You might consider replacing the word "mineralization" with the more general term "preservation" since mineralization and permineralization are just two of the forms of fossilization. You could also add "recrystallization", "bioimmuration" and "casts and molds". You could also divide your list into general categories with their different forms listed. Maybe someone with better knowledge about these distinctions could help with this. In case you have trouble finding information on bioimmuration, I believe it is when a shell like an oyster grows up against another stationary creature (dead or alive) and preserves an impression of it on the oyster shell. I'm not sure if this would fall under the general category of a trace fossil or a mold.

Good suggestions! I hadn't heard of "bioimmuration" before.

I certainly want to have text about the different types of fossils, as well as different mineralizations. There's a lot of information I could present! Now I just need to figure out what I'm going to have space for. I'll have one table for this project.

Casts and molds should certainly be included, and I have some nice gastropod endocasts in limestone, and some good brachiopod impressions in shale. I also have brachiopods and horn corals that have been geodized.

I have a lot to think about and research!

[MarleysGh0st]

On February 2nd, the Finger Lakes Mineral Club will be having an open house event at the Museum of the Earth in Ithaca, NY. We're in the planning stages now, and I'm working on assembling the displays I want to bring.

February 2 is the next Winter Free Day at the Museum of the Earth, so you should have a big crowd!

[Mediospirifer]

February 2 is the next Winter Free Day at the Museum of the Earth, so you should have a big crowd!

That's why we're doing it then!

[Mediospirifer]

The open house went well. My husband and I are both tired, but also satisfied with the day. We didn't have someone counting visitors this year, but the end-of-day estimate is that around 150 people came in to look around.

My husband and I each put together two tables worth of display materials. He focused on meteorites, using things we've put together for our annual planetarium talk. I focused on fossils: one table on different types of preservation, and one on microfossils.

Here's the meteorite displays:

Both of us spent most of the afternoon talking!

Of the mob of visitors, there were more than a dozen kids who enjoyed looking at my micros with the microscope. Including a couple who didn't say anything to me, but spent 20 minutes each looking at every speck in each of the 10 coin cases I brought!

I think the most common question I was asked was "How did you find these?" To which I answered by pointing at my chunks of matrix and saying "Well, I started with a piece like that..."

The fossil preservation display also attracted a lot of attention. I don't know if anyone actually read any of the information that I had posted on the board--they were all looking at my rocks!

I don't have a good photo of the rocks, unfortunately. (Did I mention I spent most of the afternoon talking? I didn't have time to take more than a few photos!) I'll photograph them and post pictures here as I unpack them and put them away.

Thank you to everyone who provided suggestions! My display was better for having your support.

[Wrangellian]

Looks good.. I like the 'Meteowrong' display. For the same reason, I think it helps to have a display of common/local pseudofossils to accompany real ones at a rock/fossil show, but I am still debating over whether I want to collect them - Things here have gotten a little out of hand as it is with the real fossils! I have a few, anyway.

Most people don't read much, especially if you put too much up, but I suppose that material is helpful to have anyway in case anyone wants to spend that time (and you're too busy to answer everyone's questions or they don't know what to ask).

I guess you need to take all your pictures before the show begins or after it ends before you begin to pack up.. but I know how it is forgetting stuff all the time...