Black Cat Mountain Trilobites

[ClearLake]

I have been collecting fossils for a long time but am fairly new to preparation beyond scrubbing and light picking.  I had the opportunity to collect at the Bob Carroll quarry near Clarita, Oklahoma last month.  We got chased out by rain after just a few hours and  when I left I wasn't sure whether I really had any decent trilobites or not.  I knew I found some nice brachiopods and some cool trilo-bits (even the tails of the Huntoniatonias are pretty neat) but beyond that nothing else was obvious.  I'm still working through the material  I collected but I wanted to solicit some advice on two that I am working on as I have never really done this much prep on any specimens.

 

The first one is a Paciphacops campbelli that was just a glimmer of hope:

After working on it for a while with an air scribe and air abrasive (dolomite) I have gotten it to this stage:

 

[ClearLake]

I am fairly pleased with the results so far, I know the base could be cleaned up a lot.  The preservation and detail on these specimens is pretty great, even for a relatively "basic" species such as this.  Here are two other pictures:

 

You can see there is still some stubborn matrix film on the face especially.  It just will not seem to come off and I worry about too much air abrasive work eroding some of the detail of the fossil.  Should I just keep at it?

[ClearLake]

The second one started out looking like this:

 

 

 

[ClearLake]

After a few sessions with the air scribe, I got it to this stage:

[ClearLake]

Since then I have exposed as much as I plan to, manually picked some of the matrix and hit it with the air abrasion multiple times (dolomite).  I think this is a really nice looking Reedops deckeri (II believe the genus may have changed to Lochkovella) and would like to get it as clean as possible.  Do I just need more time/patience with the air abrasion, or is there some other method to get the last bits off?  I would appreciate any advice anyone has to offer, especially if you have worked with this Haragan Fm. matrix before.  At times this limey mud can be pretty soft but other spots are quite hard.  Thanks

[minnbuckeye]

Nice finds! Am curious for responses to your question.

[Mark Kmiecik]

The least invasive method that can focus directly on matrix and matrix only will always give you the best results. I would lean towards hand-picking the rest with a pin vise.

[piranha]

2 hours ago, ClearLake said:

 

 

This one is Kainops raymondi.  Paciphacops campbelli has 3 or occasionally 4 lenses per lens file. 

 

 

Hansen, G.P. 2009
Trilobites of Black Cat Mountain.
iUniverse, Inc. Publishing, 385 pp.

[Kane]

11 hours ago, ClearLake said:

Since then I have exposed as much as I plan to, manually picked some of the matrix and hit it with the air abrasion multiple times (dolomite).  I think this is a really nice looking Reedops deckeri (II believe the genus may have changed to Lochkovella) and would like to get it as clean as possible.  Do I just need more time/patience with the air abrasion, or is there some other method to get the last bits off?  I would appreciate any advice anyone has to offer, especially if you have worked with this Haragan Fm. matrix before.  At times this limey mud can be pretty soft but other spots are quite hard.  Thanks

 

Well done so far! In terms of prep of the gunk between the segments, it will take a bit more patience with the abrasion, and attacking it from different angles. I tend to swap that out with some occasional pin vise picking to loosen it up a bit. Sometimes just scratching the surface of the stubborn matrix is enough to get the abrasion to "catch" and pop off the bits. As for the remaining matrix on the glabella and other surfaces, sustained abrasion will likely work, just so long as you aim it at an acute angle rather than directly on it to avoid overblasting the sections that are already matrix-free. You might also consider mixing in a bit of baking soda in your medium; although the moh's is softer than the limestone, the more jagged shape of the baking soda crystals might help. But I hear you about the matrix... It is not always consistent in density or mineral composition, leading to some frustrating moments, and that seems the case for most matrix types!

 

If anything, I find it takes as much time to remove the last 1% of the matrix as it does the first 99%.

[ClearLake]

12 hours ago, piranha said:

This one is Kainops raymondi.  Paciphacops campbelli has 3 or occasionally 4 lenses per lens file. 

 

Excellent catch, thanks @piranha!  I had it correct in my notes but then put it wrong in my database.  I did find several nice partials of Paciphacops campbelli, but no whole ones yet.  I also found a free cheek plate of a Kettneraspis which just makes me look even harder for a whole one as that is a very neat looking trilobite.

Edited May 27, 2019 by ClearLake

[ClearLake]

3 hours ago, Kane said:

I tend to swap that out with some occasional pin vise picking to loosen it up a bit

Yes, that is what I have been doing also to get it to that stage, I will continue until all the matrix is gone!

 

3 hours ago, Kane said:

As for the remaining matrix on the glabella and other surfaces, sustained abrasion will likely work, just so long as you aim it at an acute angle rather than directly on it to avoid overblasting the sections that are already matrix-free. You might also consider mixing in a bit of baking soda in your medium; although the moh's is softer than the limestone, the more jagged shape of the baking soda crystals might help.

Thanks for the suggestion, I will give that a try.

[Fossil-Hound]

Gorgeous

[ClearLake]

2 hours ago, Fossil-Hound said:

Gorgeous

Thanks

 

I'll have to post some updated pictures as I believe I have them about as clean as I am going to get them.  Thanks to @Kane for his suggestions, I tried the baking soda/dolomite mix and that seemed to help along with some more scratching at the stubborn spots.

 

Do folks coat these types of trilobites with PVA?  They seem pretty "sturdy" but I wonder if it would help long term or make them look even better.