Breaking down Martin Marietta Marl Matrix

[TroyB]

Okay, for all my friends who asked how I breakdown the matrix and look at it, this is how I breakdown the Martin Marietta Cretaceous marl type matrix. The Matrix I work, is from Martin Marietta Cement Quarry 5-8 inch thick phosphate pebble layer.

1. It starts with placing about 20 pounds or fill 1/2 of a 5 gallon bucket with the raw matrix.

2. Then I add about 4 bottles of Hydrogen Peroxide, to cover the matrix completely. Let this set for at least 24 hours. Then, it will be broken apart enough to sift.

3. I Sift it 5 different sizes. 1/2", 1/4", 1/8", 1/16", and 1mm. What falls thru the 1mm sifter, I usually use a gold panning technique to remove the remaining dirt, as the phosphate (everything black fossilized) is heavier than the marl type matrix.

4. Once sifted, I allow it to dry in the sun. This seams to setup or harden the fossils somewhat.

5. After a complete drying, I place them in individual ziploc bags and write the location and what it is on the bag. These are stored for rainy days when I can't get to the field to hunt.

6. Now it's just looking thru it under magnification to find the fossils. I use a 2-180X AMScope inspection microscope with wide field of view.. I made my own tweezers to fit my hand.Took a pair of curved tweezers and filed down the tip to allow picking up finer materials, roughed up the grabbing side of the tip with a file, and added a shaped wooden handle to fit my hands.

I find about 5 aprox. 1/2" fossils per 20 pounds of matrix. I find several hundred small to micro fossils as well.
 

[Tidgy's Dad]

Very interesting, informative and useful, thank you. 

[Auspex]

Great photo-essay!

Your custom tweezers are The Bomb

[Heteromorph]

I have had over 100 lb of this stuff sitting in my garage/conversion since April and have been waiting until I could properly process it! Thank you so much! 

 

I have heard that letting chunks of this rock sit in Hydrogen Peroxide could mess with any pyrite fossils in it, like pyritized ammonites. Is that true?

 

Also, I found a fragment of an ammonite steinkern in the phosphate layer. I assume that extracting it with picks would be the best method?

[Auspex]

1 hour ago, Heteromorph said:

I have heard that letting chunks of this rock sit in Hydrogen Peroxide could mess with any pyrite fossils in it, like pyritized ammonites. Is that true?

Hydrogen Peroxide is a rather weak acid, and might be rough on unstable pyrites (like those from some sites in the UK), but I have not heard of it being destructive to more stable specimens. I would give them a good rinsing afterward, though.

[Heteromorph]

10 minutes ago, Auspex said:

Hydrogen Peroxide is a rather weak acid, and might be rough on unstable pyrites (like those from some sites in the UK), but I have not heard of it being destructive to more stable specimens. I would give them a good rinsing afterward, though.

Does that mean that it would be rough on enamel if not rinsed off afterwards? 

[Auspex]

1 minute ago, Heteromorph said:

Does that mean that it would be rough on enamel if not rinsed off afterwards? 

I doubt it, but I rinse everything, no matter what chemical was involved.

[TroyB]

6 hours ago, Auspex said:

Great photo-essay!

Your custom tweezers are The Bomb

Thanks Auspex. I needed them to fit better in my hands. hehe

 

[TroyB]

6 hours ago, Heteromorph said:

I have had over 100 lb of this stuff sitting in my garage/conversion since April and have been waiting until I could properly process it! Thank you so much! 

 

I have heard that letting chunks of this rock sit in Hydrogen Peroxide could mess with any pyrite fossils in it, like pyritized ammonites. Is that true?

 

Also, I found a fragment of an ammonite steinkern in the phosphate layer. I assume that extracting it with picks would be the best method?

I haven't seen any issues with true iron pyrite and HP. Now marcasite is a different story. I'm not sure if it can be saved in the humid environment around Houston. Definitely don't want any water around it as it releases Sulfuric Acid and dissolves the specimen. Maybe test a sample that your willing to loose, first.