Florida Calcite Coral Finger or Fulgurite?

[Bronzviking]

 

Hello again, This is an interesting find found at the causeway in Tampa Bay, Florida last year. Looks like calcite covered coral or a sand fused fulgurite which I'd prefer to add to my collection, lol. What do you guys think? Thanks!

 

[minnbuckeye]

I will speculate in favor of fulgurite!

[Carboniferouspat]

I concur fulgurite.

[Bronzviking]

1 hour ago, minnbuckeye said:

I will speculate in favor of fulgurite!

I like that answer but I read most fulgurites are hollow and mine isn't.

[minnbuckeye]

The one end appears to have an opening.

[GeschWhat]

Tough call. fulgurites usually have a really smooth glassy interior. Yours looks like it has a calcareous interior. You could try putting a drop of vinegar on the sandy portion to see if it fizzes. If it does, I doubt it is a fulgurite.

[grandpa]

The 4th photo in the OP shows what appear to be vertical ridges along the "stem" of the specimen before it gets covered up with the "coating".  Could you get a closer view of these structures.  I'd like to see if they show any sub-structure.  The vertical  structures don't conform with the idea of fulgurite to my way of thinking.

[Bronzviking]

11 hours ago, GeschWhat said:

Tough call. fulgurites usually have a really smooth glassy interior. Yours looks like it has a calcareous interior. You could try putting a drop of vinegar on the sandy portion to see if it fizzes. If it does, I doubt it is a fulgurite.

Surprisingly it does Not fizz with vinegar but it does have a calcareous core like you pointed out. What now?

[Bronzviking]

11 hours ago, grandpa said:

The 4th photo in the OP shows what appear to be vertical ridges along the "stem" of the specimen before it gets covered up with the "coating".  Could you get a closer view of these structures.  I'd like to see if they show any sub-structure.  The vertical  structures don't conform with the idea of fulgurite to my way of thinking.

I zoomed in on the stem. This is why I questioned fulgurite too, but it sure looks like fused sand and didn't fizz with vinegar so we can rule out calcite right?

[GeschWhat]

1 hour ago, Bronzviking said:

This is why I questioned fulgurite too, but it sure looks like fused sand and didn't fizz with vinegar so we can rule out calcite right?

Yep. Does the "stem" fizz?

[Bronzviking]

5 minutes ago, GeschWhat said:

Yep. Does the "stem" fizz?

No it doesn't. So what is your conclusion?

[GeschWhat]

I don't know that much about fulgurites. I have a couple from Morocco. I'm guessing it was fused by heat. I wonder what fulgurites look like when lightning hits something other than sand. If it were me, I would take a blowtorch to a piece of fossil coral to see what it does. Test it with vinegar before and then test it again if it survives a blowtorch test. Have any coral pieces you don't care about? If you do this, be sure to wear safety glasses. 

[supertramp]

14 hours ago, grandpa said:

The vertical  structures don't conform with the idea of fulgurite to my way of thinking.

maybe something along Dentalium sp.?

[grandpa]

The latest pict still leaves me doubting fulgurite.  If possible, I would like to see a closer photo of the "ridges of the core" showing the micro-structure of the "ridge" area.  It looks like the one prominent ridge in the pict has "sections" along its length.  That is also a curious feature and may be helpful in ID with magnification.  I'm not sure what I'm seeing, but it gives me the sense of an organic core as opposed to a fulgurite.  Don't know if this helps; maybe someone will recognize the core structure.

[Bronzviking]

On 5/19/2020 at 1:05 PM, GeschWhat said:

I don't know that much about fulgurites. I have a couple from Morocco. I'm guessing it was fused by heat. I wonder what fulgurites look like when lightning hits something other than sand. If it were me, I would take a blowtorch to a piece of fossil coral to see what it does. Test it with vinegar before and then test it again if it survives a blowtorch test. Have any coral pieces you don't care about? If you do this, be sure to wear safety glasses. 

Thanks for your input but I don't have a blow torch or insurance, Lol.