Echinoid in rough shape

[MrBones]

Hello,

I found this echinoid the other day, and I was hoping to clean it up. Unfortunately, it's in bad shape. This is the only one I have of this type, so I would like to make it presentable. I found it on Jebel Hafeet, Al Ain, UAE (United Arab Emirates). The fossil appears to be covered in calcite, plus the rock there is mainly made up of limestone. I heard that the "vinegar bath" isn't such a good idea, what else can I do?

 

[caterpillar]

You can try the white vinegar but very diluted. When you dip the sea urchin in it, you can barely see the bubbles. Me, I do this by ear. I listen if it crackles. And above all, you watch. Every 2 hours, you look, you brush and you re-soak in it. But it may be long

[MrBones]

6 hours ago, caterpillar said:

You can try the white vinegar but very diluted. When you dip the sea urchin in it, you can barely see the bubbles. Me, I do this by ear. I listen if it crackles. And above all, you watch. Every 2 hours, you look, you brush and you re-soak in it. But it may be long

Thank you for the response! So must I add some water to the vinegar? Also, what exactly do you mean by "brush", is it just to test its integrity?

I assume you'd know when to stop (when it looks better.)

[JohnJ]

To my eye, this echinoid has had its surface eroded beyond any potential cleaning.  I would leave it as is.

[MrBones]

5 minutes ago, JohnJ said:

To my eye, this echinoid has had its surface eroded beyond any potential cleaning.  I would leave it as is.

I would also like to leave it, but it's hard to make out what it actually is without looking really hard.

[caterpillar]

1 hour ago, JohnJ said:

To my eye, this echinoid has had its surface eroded beyond any potential cleaning.  I would leave it as is.

 

Yes, much of the shell is gone. The vinegar test can show the parts of the shell that remain.

And yes, you have to dilute the vinegar with water.

But you can also leave it as is.

[LabRatKing]

This fellow looks to be pretty cherty and as others have said is heavily weathered. A vinegar wash will not do any good and likely dissolve the details of the fossil without even harming the cherty encrustations.

[MrBones]

8 minutes ago, LabRatKing said:

This fellow looks to be pretty cherty and as others have said is heavily weathered. A vinegar wash will not do any good and likely dissolve the details of the fossil without even harming the cherty encrustations.

I see. That's a bit of a shame, but I'm still proud of my find. I have discovered some soft matrix under the fossil, which, when removed, shows some more detail.

[LabRatKing]

9 hours ago, MrBones said:

I see. That's a bit of a shame, but I'm still proud of my find. I have discovered some soft matrix under the fossil, which, when removed, shows some more detail.

It is a good find! And now you know a spot that has great ones hiding!

[caterpillar]

16 hours ago, LabRatKing said:

This fellow looks to be pretty cherty and as others have said is heavily weathered. A vinegar wash will not do any good and likely dissolve the details of the fossil without even harming the cherty encrustations.

In France, we often prepare calcite urchins included in a very hard limestone matrix with baths in very dilute acetic acid. This gives very good results. But it is true that you have to master the technique otherwise the result can be catastrophic.

Here an example with a Cidaris in a coral limestone (more than very hard!)

 

 

And after monthes of prep in acide acetic baths

 

 

[MrBones]

11 minutes ago, caterpillar said:

In France, we often prepare calcite urchins included in a very hard limestone matrix with baths in very dilute acetic acid. This gives very good results. But it is true that you have to master the technique otherwise the result can be catastrophic.

Here an example with a Cidaris in a coral limestone (more than very hard!)

 

 

And after monthes of prep in acide acetic baths

 

 

That is amazing. Certainly not something I'm prepared for, but still so amazing.