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I enjoy sorting through micro-matrix. Between the times that I'm able to spare a Saturday to drive 3 hours to the Peace River to sift for larger fossils, I like to have some micro-matrix on hand so I can easily scratch the itch when I feel the need to hunt for fossils--even if it is only from the comfort of my office desk. I'm currently working on a project involving micro-matrix (which I'll write-up on TFF once it is complete). This project requires a large number of specimens and so I've collected about five 5-gallon buckets of micro-matrix which now reside in the corner of my home office. Whenever I need a break from working on the computer I can easily grab a cupful of micro-matrix, my omni-useful dental probe, and my well-worn iris decorated paper plate and take a short plunge into the world of tiny fossils. I've recently taken steps to optimize my productivity while sorting micro-matrix so I thought I'd post them here in case any micro-fossil hunters find any utility in my method. Here is my usual setup for sorting micro-matrix--I used to pour out a large amount of micro-matrix onto my plate at one time but I now sprinkle a narrow, nearly complete, ring of micro-matrix around the edge of my paper plate. I use two different colored cups to keep track of which cup I'm pulling from and which cup I'm discarding from. I used to use two blue plastic Solo cups but it's no fun when you get them mixed up and start sorting your discards instead of fresh micro-matrix. Color coding has solved that issue permanently. I purchased a nice large magnifying lens ringed in 100 LED lights which provide nice even lighting in the field of view. The model I purchased is usually made for those doing detailed crafts like needlepoint or those whose vision is not what it was when they were younger so they can minimize eye strain while reading or doing crossword puzzles. As this model is specifically meant to be used while seated, it comes with a heavy weighted base and an adjustable arm so I can move the lens around and adjust the height over my plate for optimal focus. I used to scan micro-matrix using my photographer's loupe which had became rather outdated and useless once I went digital and stopped processing chemically developed slide film. The problem with this is that holding it in front of one eye with the other eye closed for extended periods caused only one eye to focus abnormally close and after a session of micro-fossil hunting my vision would end up blurred for hours afterward--not ideal in any way. The large lighted lens was not inexpensive but being able to see my micro-matrix clearly with both eyes providing some stereoscopic depth and no residual eye strain made the purchase well worth the cost. Though the camera could not quite figure out where and how to focus while viewing through my magnifier, you'll get some idea of how I see my micro-matrix under well-lit magnification. I've sorted many gallons of micro-matrix using just this method with great success. I'm an engineer by trade (computer programming to be specific). I'm always on the look out for ways to optimize my process allowing me to more efficiently search through my micro-matrix to find the tiny prizes hiding within. One of the things that limits my efficiency while sorting is the size range of the items in my micro-matrix. When I collect micro-matrix in the field I use a pair of stacked sifting screens. The top screen has 1/4" mesh and screens out any pieces larger than this approximate dimension. The sifter under that has a piece of metal window screen placed inside it. The mesh spacing on this screen is approximately 1/20". The separate piece of screen material allows me to lift this out of the bottom sifter and flush some of the fine sand through this tighter mesh before dumping it into my collecting bucket. So my collected micro-matrix consists of pieces roughly between 1/4" and 1/20". The mixture of different sized pieces can be seen in the last photo above where larger chunks of black phosphatic pebbles and shell hash mingle with smaller pieces of rock and sand. While sorting through this micro-matrix my search image has to encompass larger shark teeth and ray tooth plates all the way down to tiny drum fish "button" teeth, Dasyatis stingray teeth, fish incisors, and tiny baby shark teeth. I'm pretty good at keeping all of these search images in mind while working through the micro-matrix but consider the scenario of being out on a South African safari and trying to keep an eye out for a heard of African Elephants, a clan of Meerkats, as well as looking out for Dung Beetles rolling by. You might be able to be on the alert for any of these African photo-ops but it would be hard not to know if you'd overlooked something somewhere. I remembered visiting the Florida Museum of Natural History (FLMNH) up in Gainesville a little over a year ago and getting a spectacular tour of the work area where specimens were being prepped and micro-matrix from the Thomas Farm dig site was currently being processed. Dr. Hulbert explained to me and my wife how the bagged micro-matrix from the field was washed through a stacked set of sifting screens with different mesh sizes before being placed in a drying rack where continuous air flow sped up the drying process. I also recently learned that each project (Thomas Farm, Montbrook, etc.) have their own sets of screens to avoid any cross contamination that might make for interesting mix-ups of fossils.
Made these sifters out of milk crates, bought from Hardware store and cut them down to few inches from bottom. Have 1/2", 1/4" and then 2 smaller wires. Stack them up on the bed of my work truck and let the yard do the sifting as I drive around.