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Optimizing micro-matrix sorting

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Yvie

Hi have you tried a digital microscope connected to a computer?Even less eye strain and they are cheap and cheerful now,mine is 5mp.

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Al Dente

Ken

I think your barbed fossil is a catfish pectoral spine. 

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Fossildude19

Ken,

Thanks for this most excellent breakdown of your micro-fossiling techniques.  

Your thread has been pinned.   @digit

Regards,

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ynot

Nice guide Ken.:dinothumb:

 

Tony

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caldigger

Coming from a gold prospector, your assessment on the sizing of material is spot on. The closer you can get the grain sizes of material to be worked the better it will stratify. If all the material is the same size, gold will always win out.

And who says size doesn't matter?

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digit
21 minutes ago, Fossildude19 said:

Your thread has been pinned.

 

My first "pinning"--thanks. I've gotten so much from this forum that I'm always looking to give back in any way I can. I'm nowhere near as knowledgeable as many on this forum (in fact, most of my fossil knowledge was derived from reading the postings of other members here). I try to find ways to contribute and, as you can clearly tell, I'm an inveterate story teller and so I try to impart my experiences to this forum--either collecting in the field or working on what's been collected. Though I'd never have made it as a photo journalist, I do think in pictures often and I like to illustrate my posts when possible to convey my story.

 

My hope is that my modest success in optimizing my method of sorting micro-matrix might give others some ideas which might benefit them.

 

 

Cheers.

 

-Ken

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Yvie

I agree with depth of field,someone on our British forum mentioned using a polarising filter but I haven't tried that yet,but I do use an led light powered by the computer for side illumination.I'll have to have a play with my canon.Thanks for the info.

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jpc

Thanks for this info.  I am more like al dente... I screen to two different fractions, not your 5 or 6.  The other thing I do differently is I sort on a blank 5 x 8 piece of cardstock.  I have a pile of unised mailings form someone from the distant past that are blank on the back.  I fold the top (long side) and bottom up and then draw lines in at about 3/8 inch.  I also have lines on the short sides that say, do not put matrix outside these lines.  The folded up edges keep matrix on the card as well.  The lines create 'alleys' parallel to the long axis of the card  so that when I am looking through the microscope (I sort through my binocular scope) I can just scan along the parallel alleys I have drawn and slowly move from side to side, jumping down one alley each time.  NO need to move the rocks to know I have looked at them.  I also try to spread rocks thin enough so that I do not need to move them out of the way of each other.   

 

I will try to post a photo over the weekend, but I am on my lunch break at the office now. 

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digit

Illuminating fossils with polarized light to effectively produce polarized light microscopy might be interesting. I've seen this technique used mostly with thin film sections in optical mineralogy. Doing a google image search for "optical mineralogy" will return some fascinating (and beautiful) images.

 

If you are instead referring to just placing a polarizing filter in front of the camera lens then I'm not sure what benefit this might bring. I use my polarizing filter for my DSLR camera to remove the glare and aid color saturation when taking photos of reflective surfaces in bright sun (the surface of a body of water being the prime example). I guess this could possibly have some beneficial effect but my view of micro-fossils through a camera's lens has never been marred by any lighting that a polarizer might resolve.

 

The thought did just occur to me that when using the Helicon Remote software to control my Canon DLSR (a 5D Mark II) that the software puts the camera into "live view" mode so that I may view the focus on my computer's LCD screen. This is useful while also using the software to nudge the camera lens focus motor one step at a time to achieve precise control over the nearest and farthest points of the focus when setting up for shooting a stack of photos with different focal planes which are later combined by the Helicon Focus software into a single image with a super-optical depth of field. Pumping what is, in effect, realtime video through the USB cable to my computer tends to eat up my camera's battery during extended photo sessions but I suppose that if I could find an external power supply for my camera and rearrange the photo setup in my office, I might be able to reproduce a higher quality version of the functionality of my cheaper Celestron "digital microscope". I don't recall seeing any particular delay when viewing my Canon DSLR through the software (though I may just not be noticing it as I'm only staging specimens for photos rather than sorting through a plate of micro-matrix). I have much better control over the depth of field on this setup as well as my macro lens has the adjustable aperture diaphragm to control the f-stop.

 

While viewing tiny specimens in realtime (or nearly so) on my computer screen can be useful--especially for micro-photography, I think I still prefer the low-tech solution of a brightly lit large diameter magnifier while sorting. This is the specific model I'm using but there are hundreds of models available online:

 

http://www.firststreetonline.com/Home+Solutions/Magnification/High+Power+Page+Magnifier.axd

 

 

Cheers.

 

-Ken

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digit
12 minutes ago, jpc said:

I will try to post a photo over the weekend, but I am on my lunch break at the office now. 

 

Would love to see your setup when you get a chance to post photos. See how other people attack the same problem can provide novel ideas even if the entire method is not used.

 

I do find that most of the specimens that I'm particularly interested in from this micro-matrix tend to be found in one or two of the sifting screens (mainly the 1/8" and 1/12" screens) and the full complement of 9 screens is indeed overkill. The fractioning of my micro-matrix into multiple different particle sizes is informative in being able to isolate one size class to pay special attention to micro-fossils of a certain scale. I can foresee using specific combinations of these screens to optimize my micro-matrix collection in the field so I can take home just the appropriate size class of micro-matrix for the specimens I am in search of. A few of these screens will likely receive the lion's share of attention and use but I like having the full complement to be able to experiment. Different types of fture micro-matrix from different localities may direct my attention to micro-fossils of different size classes.

 

 

Cheers.

 

-Ken

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Yvie

Dr Steve Sweetman has been sieving a beach on the Isle of Wight,discovered 48+ New species.Happy hunting!!

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digit

Nice! He was off my fossil radar--just looked him up online. Looks like he has tapped into exposures there from around 130 mya containing dozens of species from dinosaurs, lizards, frogs and salamanders to some of the early small mammals. Says he's sieved through tons of sediment to find these microscopic fossils. Sounds like a kindred soul who I could talk to for hours over a pint or two.

 

Cheers.

 

-Ken

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sixgill pete

Ken, I use almost the exact method you use.  have a set of the same sieves you have, however I normally do not go down any smaller than .5 mm on my screening. I start with the 1/4, then sift out any thing smaller than 1mm. then I sift it down to .5. 

 

I often use the sieves with large chunks of matrix. I set them out in the yard with the matrix in them and let the rain break the chunks down. This sometimes can take more than a year, but some of the finds are amazing.

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JohnJ
41 minutes ago, sixgill pete said:

....

 

I often use the sieves with large chunks of matrix. I set them out in the yard with the matrix in them and let the rain break the chunks down. This sometimes can take more than a year, but some of the finds are amazing.

 

I don't have the patience to wait a year.  :P  However, I agree with your results.  I'll use the outdoor water hose to gently shower my matrix.  There is a noticeable difference in how many more fragile specimens survive the sift/sort process.

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sixgill pete
20 minutes ago, JohnJ said:

 

I don't have the patience to wait a year.  :P  However, I agree with your results.  I'll use the outdoor water hose to gently shower my matrix.  There is a noticeable difference in how many more fragile specimens survive the sift/sort process.

 

I do sometimes with the softer matrixes, "help" them along with the water hose. But the harder matrixes, mother nature is the best dissolver. Sometimes clay / dirt mix matrixes I just leave in a large container of rainwater to soften them before washing.

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Canadawest

Great info in above postings.

 

There are fascinating specimens waiting to be discover at the micro level.  We all borrow on other techniques then usually modify them for our own use.

 

I've had a set of  4 stacking sieves for decades.  Light weight and indestructible. These were considered 'the standard' for reporting to various departments for mining applications, etc.

 

I get matrix and either use 'as is' or dissolve it using acids.  Then sift through the series of sieves and sort under low power with the microscope.  I usually keep the light off and use a fiber optic light that can be adjusted at different angles from the side. This oblique angle gives more relief and easier to find specimens...especially the smallest.

 

These are specimens various sizes of Late Devonian and Early Carboniferous shark teeth.

IMG_6287.JPG

IMG_6289.JPG

IMG_6290.JPG

IMG_6291.JPG

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digit

About a year ago I had the honor of meeting up with @ynot at Shark Tooth Hill in Bakersfield, CA. It had rained heavily the week before (even washing out some of the roads over at the Ernst Quarries. Tony brought along his 1/4" shaker-table sifting screens so that we could check the matrix that we removed while looking for larger shark teeth to see if any smaller ones were hiding (which they were--we recovered quite a few from the sifting screen). The matrix that fell through the sifting screen was collected in a couple of 5-gallon buckets to be searched for micros once I was back home. The rain hampered the collection of micro-matrix as it left the matrix rather damp and the little lumps of clumpy matrix that passed through the sifting screen looked like a very unappetizing dried cat food.

 

I carted the two full 5-gallon buckets back to my brother-in-law's house where I had access to a hose and a fine mesh colander. Emulsifying the muddy matrix and then straining it reduced the 10 gallons of matrix enough to fit into 2 gallon size zip-top bags (after drying). There was still a lot of chunky matrix hiding the fantastic variety of micro-fossils and I attempted to soak and strain it again. After being completely dried out the second washing dissolved much more of the matrix and I was left with about a quart size baggie of concentrated matrix (containing some really nice shark teeth and other micros). My guess is that the matrix contained a lot of silty clay-like material and the first contact with water formed a gel-like coating on the matrix nuggets inhibiting further breakdown by the water. The intervening drying likely caused the nuggets to shrink and develop cracks which allowed a second soaking to penetrate and dissolve away more of the matrix. As an experiment, I allowed the paltry remaining bag of concentrated matrix to dry again in the sun but a third soak didn't seem to remove any significant amount of material so I figured I was down to just harder chunks that would not dissolve with water. I experimented with small batches of micro-matrix (after I had sorted through and pulled out all the micro-fossils I could see). I added a bit of acetic acid (vinegar), hydrogen peroxide, and other chemicals I thought might break down the matrix without dissolving away everything. Never found anything that would dissolve the remaining matrix to see if there were any last micro-fossils hiding within. I was surprised though how well a soak-dry-soak routine did. The micro-matrix I collect from South Florida is basically shell hash and phosphatic, silica, and carbonate based rocks without any clay that would need to be dissolved and removed. Basically, a wash to float away residual vegetative matter like tiny leaf fragments, a good drying on a tarp in the sun, and some sifting to remove the residual sand is about all that is needed. And now I have more than enough sifters to perform whatever type of sifting I need.

 

 

Cheers.

 

-Ken

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Bone Daddy

@FossilDudeCO - I tagged somebody for this. This is good to know when dealing with this matrix material. I too had some from south Florida (the shelly phosphatic mix) and it breaks down fairly easily. The material I had did have some clay constituents, and it's fairly heterogenous, so some chunks have more clayey texture and some pieces are very loosely consolidated and friable - they break apart readily without being soaked or strained. The latter is easier to work with, but the former seems to have more treasures concealed (vertebrates). I find the loose very-shelly or beachy stuff is almost all Miocene and Pliocene inverts and the clay-ey stuff has the mammals and later Pleistocene goodies.

 

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