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kingcobb

Ammonite and some muriatic acid

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kingcobb

I had this weathered ammonite fossil I had found in a load of rocks dumped by the highway department under a bridge.  It was weathered and not in fantastic shape but it had a lot of limestone on it still.

 

Used some muriatic acid on it and let it soak in water and baking soda to neutralize it.  Still not a great specimen, but it removed a lot of rock.

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Ludwigia

You probably removed some of the ammonite as well, since it's also made up of limestone.

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grandpa

That's not so bad at all; it's just starting to show its age. <_<

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kingcobb

I don't think I lost any actual fossil material.  I was pretty precise with where I applied the acid and for short amounts of time. I suppose it's possible but in person it isn't noticeable if I did.  Main difference is the color is gone but the spines are definitely more pronounced and the interior is no longer solid rock.

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Ludwigia
9 hours ago, kingcobb said:

I don't think I lost any actual fossil material.  I was pretty precise with where I applied the acid and for short amounts of time. I suppose it's possible but in person it isn't noticeable if I did.  Main difference is the color is gone but the spines are definitely more pronounced and the interior is no longer solid rock.

Well, as long as you're having fun.

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Shamalama

I'm guessing you are in Texas by the brochure in your pictures, so I would say you might have a Mortinoceras sp. Ammonite.  Depends on where the rock you found it in came from, but the Duck Creek formation has lots of that genera of ammonites present.

 

@Uncle Siphuncle  might be able to tell better than I as he is an expert in all things Texas and Cretaceous.

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kingcobb

Yeah I have a few found ones that have been prof prepped from duckcreek.

 

This one was from wherever the load of limestone used by tx dot came from.

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Uncle Siphuncle
1 hour ago, Shamalama said:

I'm guessing you are in Texas by the brochure in your pictures, so I would say you might have a Mortinoceras sp. Ammonite.  Depends on where the rock you found it in came from, but the Duck Creek formation has lots of that genera of ammonites present.

 

@Uncle Siphuncle  might be able to tell better than I as he is an expert in all things Texas and Cretaceous.

This looks typical for Duck Creek and Fort Worth Mortoniceras ammonites, the 2 formations where they tend to run largest.  I'd probably start with comparison to M. inflatum.  

 

I too have used spot application of muriatic acid on Lower K ammonites with good results.  I've used Q-Tips to dab acid on scribe marks left when chasing the juvie whorls inward to where they often disappear and become indistinguishable from the matrix plug.  To my eye, this technique knocks those white marks down a shade or two, leaving a mistake less unsightly than when left raw and disturbed.  If done with precision and dwell time of seconds before rinse, additional detail is not unnecessarily compromised, mainly because you "color between the lines".  But any mention of such draconian prep techniques tends to draw mixed comments.  These days, I tend to prep less in order to avoid a situation that potentially requires surface restoration, the goal being a natural presentation.  Acid is a last resort for me.

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hrguy54

I have been using diluted muriatic acid as part of my prep process for years. And years. And my stuff looks real good. Have mentioned it in TFF before.

I use about a 10 or 12 to one ratio water to acid. 

I have purposely left low end fossils in the solution for prolonged time to see what happens.....what you would expect.

I recently had a conversation with JamieLynne (also of TX) about this very thing.  We agreed that what may be very effective on SW and NW Ohio fossils may not be so effective on specimens from other areas.

You don't know till you try.....on an inferior piece.

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RJB
On 11/10/2019 at 2:11 PM, kingcobb said:

I don't think I lost any actual fossil material.

You most definetly lost some shell, but as Ludwigia already said,  "as long as your having fun".   Everyone here on the forum is/has/will be finding and  learning about prepping fossils.  Just take your time and have fun.  Lots of info here to help you.

 

RB

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grandpa
49 minutes ago, hrguy54 said:

I have been using diluted muriatic acid as part of my prep process for years.

I recently had a conversation with JamieLynne (also of TX) about this very thing.  We agreed that what may be very effective on SW and NW Ohio fossils may not be so effective on specimens from other areas.

You don't know till you try.....on an inferior piece.

I agree with the quote above.  In prep'ing Texas Cretaceous fossils, I have found a judicious use of dilute HCl similar to what @Uncle Siphuncle describes above can be used without loosing essential detail of the fossl - great for large Texoma ammonites, not so much for small detailed echinoids.  But like other skills, it depends on the level of capability you have in fossil prep.  For @Ludwigia and folks of his talent, I'm sure this sounds like heresy; for folks not so far along on the curve, this is a start.  Just don't take a rare or finely detailed fossil and submit it to this.  That should be reserved for more professional prep.  But if you happen on a run-of-the-mill duck creek ammonite that is a common species, and you can make it look better to your eyes by submitting it to muratic acid; hey it's yours to do with as you wish.  Just be SURE it isn't something of scientific significance before you do, because something will be lost in the process.

51 minutes ago, RJB said:

You most definetly lost some shell

That is a great point - IF the fossil has any shell.  What we're talking about in this example, and in most Cretaceous fossils in Texas are steinkerns, so no shell to lose.  Again, some detail yes/maybe, if there is detail preserved to lose.  In that case, don't use this technique.  But, at least in my collection, and I'd say in the example that is the subject of this post, HCl does have a place in fossil prep.

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