Recrystallized, articulated crinoid?!

[joshuajbelanger]

So, I found this specimen across the street from my paleontology professor's "mega crinoid bonanza spot". This is an Ordovician spot in Kentucky packed full of crinoids.  I think it is a recrystallized; articulated crinoid.  But what do you guys think?  I'm about a quarter into prepping it. The pics aren't that great, but it seems to be a lot of the columal, any ideas would be appreciated.

Wow, these pics are garbage.  I'll take between ones

[FossilDAWG]

I agree, better photos would be a big help.  I cannot distinguish anything much form the photos you posted.

 

Don

[joshuajbelanger]

Wow, these pics are garbage.  I'll take between ones

These pics really aren't doing it justice.  I may have to prep it more, but what do you guys think?

[Fossildude19]

Honestly, this looks like a quartz vein, to me.  

[ynot]

Looks like a mineral vein, not a crystallized fossil.

Quartz is a good guess, but it could be calcite too. Does it scratch with a knife (the white area.)?

[joshuajbelanger]

It's most likely calcite, and I'm on the fence about it.  It's not what it's been replaced with.  I am 100% open to this being a mineral vein.  For you guys that have experience with mineral veins(which I do not) does it take shape in spherical patterns?  This was my first time hunting Ordovician, and it was a well know crinoid spot.  This rock appeared to have calcite(or quartz) columnals.  That's what stuck out to me.  But, if you guys say natural vein, then I will agree.

[ynot]

From the pictures it looks like a plane through the rock as opposed to a "tube" like structure.

It is common for a vein to be segmented by crystal growth, other minerals and vien space restrictions.

 

[Arizona Chris]

Im seeing a calcite vein, and a lot of lumpy things I cant say what the heck it is!

[jewelonly]

Hi Joshua,

I really like that you have posted this thread because I very recently dug a SUV load of geodes from KY and I had similar questions. So many of  them seemed to have degrees of conformity, plus I knew the area was also crinoid rich. Therefore, the following publication by Ray Smith Bassler, The Formation of geodes with remarks on the silification...was an eye opener. It is a free ebook at the following link.

https://books.google.com/books?id=Tc4qAAAAYAAJ&pg=PA140&lpg=PA140&dq=geode+crinoids+calyx&source=bl&ots=LCXjqvTihH&sig=0AldK3dP7kNkVOnymG83vijFgno&hl=en&sa=X&ved=0ahUKEwjVv6fElPbUAhXKPz4KHVLnAXYQ6AEIIzAI#v=onepage&q=geode crinoids calyx&f=false

It seems that crinoid, brachiopods and other calcitic organisms often provided open spaces in the rock for silica rich deposition. Sometimes these geodized fossils are found still representative of the original form, but oftentimes in the silification process, the fossil exploded and the minerals continued to grow tracing the fracture lines and then transversing them, resulting in those wonderfully knobby psuedomorph fossil geodes. I think that might be what you have. However, I am interested to learn what others think.

 

Look at these illustrations and descriptions and read this page from the ebook and see what you think about it.

 

Tomorrow, I will take specific pics of some that I have that look like yours. Again, thank you for posting such an interesting  topic!  

 

Leah

 

[joshuajbelanger]

This actually makes a lot of sense.  I can see where the vein took the shape of the columnals, and then grew outward.  It did seem a bit too large, but I'm gonna finish prepping it out anyway, might turn out pretty cool.  Thanks.

[aerogrower]

@joshuajbelanger I think in the second set of pictures you have a very interesting color nail polish on. In the last pics you need to reapply your nail polish and shave your arms.

[joshuajbelanger]

33 minutes ago, aerogrower said:

@joshuajbelanger I think in the second set of pictures you have a very interesting color nail polish on. In the last pics you need to reapply your nail polish and shave your arms.

Fossil hunting is hard on the nails! 

[jewelonly]

Joshua, here a few pics of the different geodes I mentioned. The fracture patterns are evident but I'm not sure how noticeable they are in the pics.We pressure washed these and have left them for the last month to weather. Eventually, we will cut them except for those that retain some evidence of their initial fossil form. Quite a number have the "broccoli" look of pics 1 and 2 while others have similar forms of pic 3 and 4 in varying sizes. 

 

Hope you will post a pic of yours after you finish prepping it.  

 

Leah

 

 

[abyssunder]

I agree. All the above specimens are geodized crinoid parts. Leah's examples are crinoid calyces. Often it is hard to see their original form due to the crystallization process through diagenesis, process wich make them inflated.

 

" In the case of the calyx of a crinoid, little or no fracturing is necessary to give rise to the deposition of silica, since the plate sutures furnish an excellent place for crystalline growth. " - excerpt from the document mentioned

[ynot]

I can see it being a geodized fossil.

Just did not think along those lines at first.

[joshuajbelanger]

Hopefully I'll be able to pull out a little detail.  I did collect a lot of geodes from this area too.  I remember seeing this part and thinking it definitely looked like a crinoid. The rocks really sticky though, and it's not prepping easy.  

 

Leah, I can definitely see the resemblance to our pics.  Very cool regardless!