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This ongoing journey begins as many do, with an accident. While trimming down matrix from my collection to reduce weight, in this instance a piece of the Aust bone bed, I accidentally sliced right through an ichthyosaur vertebra that I didn’t realise was there hidden in the rock. After the initial annoyance wore off, I realized that the internal texture of the bone was pretty nicely preserved and that gave me an idea, maybe I could make a histological section of the offcut piece of the vertebra. I have always wanted to learn how to make thin sections and this gave me the catalyst, so I emailed my the lab technician in my department (I study Paleobiology for my PhD) and next thing I know I was scheduled for training on how to use the departments thin sectioning and polishing lab. I hunted through my collection for a few fossil pieces that I could use as practice and decided on two Yorkshire belemnite fragments, as I have more complete examples and I thought that the rings of the belemnite would make an excellent subject. I am going to wait until I have more practice with the technique, and also have an opportunity to CT scan the block for posterity before I go grinding away what remains of the vertebra. The first test pieces: The process for making thin sections is relatively simple though it requires at least two days for the resin to cure. First you cut a wafer off of the specimen using a specialist saw which produces a very smooth cut surface. The resulting wafer from the smaller belemnite tip: Then you can bond the cut surface of the wafer to a frosted glass microscope slide using epoxy resin. These are then placed in a clamp to cure Two days later, I was introduced the thin section machine, which contains both a cutting wheel and a grinding disk with the arm attached to a micrometer. The glass slides are mounted in a vacuum chuck on the arm and then passed through the blade which cuts off excess material leaving only about 500-600 microns of sample material bonded to the slide. Next the arm is maneuvered to the grinding wheel and with successive passes ~20 microns at a time are ground off the sample until the remaining layer is only about 100 microns thick. At this point the sample is translucent and polarized light gives an idea of the crystal structure of the belemnite! Unfortunately, due to some issues with the resin mix these first two attempts didn’t turn out great but for the purposes of learning I was shown how to polish them anyway, first using a 9 micron diamond suspension which after repeat use reduces the sample to approximately 60 microns and removes the scratches from the grinding disk, then with a 3 micron suspension which does the majority of the actual polishing. Polishing slides: And here’s what the initial results look like under the microscope, I’m looking forward to trying the technique again and improving, as well as figuring out how to attach my camera to the microscope to take better pictures. The growth-rings in the belemnite are very apparent and in the one where I cut through the phragmocone end you can clearly see the siphuncle! Beautiful belemnite growth-rings from the larger specimen: The siphuncle on the edge of the phragmocone: The rings preserved in the smaller specimen: The rings at higher magnification: I’m excited to get to improve my technique and I have a few ideas for other pieces to test with. I will update this soon with more as I keep working at it. Please feel free to ask any questions you have and I’ll try to answer them. Thanks for reading, Benton

I'm interested in looking at the internal structure of fossils. I would like to try my hand at making thin sections. I found this protocol: Making thin sections by hand It looks feasible. I have microscopes and I'm willing to invest in some equipment as necessary. I would really appreciate hearing from anyone here who has made thin sections who could help me get started. Thanks Roger

In keeping with the Micro-paleontology theme I sliced up a few Mosasaaur teeth and made thin section slides. Hoping to find something resembling a cavity. There are cavities, but not the dental type. The reason my dentist said "No sugar". All of the teeth were hollowed out at the root end and filled with a soft/loose grainy mixture. A web presentation may be viewed here. Photo1 shows a sampling of the Mosasaur teeth I received from Rocks and Gems Canada. The teeth are cracked and broken as I requested a grab bag of fossils from the cutting floor. The Mosasaur teeth are much softer than I expected and the slicing, grinding and polishing went quite quickly. Photo 2 is the tooth I selected for making thin section. Photo 3 shows the sandy fill and photo 4 is through a 10x stereo microscope. The microscope view shows a wide variety of colurs that deserve closer attention. Photo 4. Many colours of the fill. Photo 5 is the cross section view at 5x with crossed polars. My search for cavities narrowed down to what look like root channels in the tooth. This is pure speculation and dreaming. My stereo microscope has a .8x to 4x optical range so photo 6 at 20x, photo 7 at 100x were taken through the Labomed LB-592 polarizing microscope with the traditional turret mounted objectives. Some of the outer surfaces of the teeth looked to be constructed of two or more layers. Photo 8 is the tooth I peeled back a bit to reveal the layers in photo 9. Photo 9. What appear to be layers in the tooth enamel Photo 10 is a closeup at 10x.

I knocked a few chunks off of a large block of Landscape Limestone, ground them down to 80 microns on a glass slide. Most of the rocks I have collected locally are rather uninteresting as thin sections. I was very surprised to see what I believe to be a lot of micro fossils on two of the slides. I checked my fossil reference guide and I can identify Crinoid stems, Shells and maybe a leaf. I assume all those rectangular things are Crinoids an their side. The average size of the objects is 200 microns. The larges being what I believe are shells at 1,59 mm. Comments welcome on my identification skills. Photo 1 is the source of the chunks of rock. Photo 2 is slide number 3 taken through a Canon Rebel XS (1000D) camera mounted on a Labomed LB 592 polarizing microscope. Photos 3 and 4 are crops of Photo 2 Photo 5 slide number 4. Part of the same chunk as Slide number 3. Photos 6 and 7 are crops of slide number 4

Can anyone suggest a good reference with lots of pictures about micro sized fossils? I would like to try and determine if the shapes are fossils of animal or vegetable matter. I make thin section slides of stones (less than 50mm in dia,) and occasionally see shapes that I think might be fossils. The shapes are small, generally less than 3mm in length and width. This is a sample of what I have found in local stones.

A Suggestion for Making Thin Sections for Bryozoan Slides Free download

Looking at a commercially made thin section of Kyanite, I thought or rather hoped the image showed evidence of micro fossils. Can anyone shed some light on these images? This link is to a full section view using Photoshop's Deep Zoom feature. http://theqcc.hennig.ca/Dec/11/index.html The photos were taken through a polarizing microscope adapter on a Stemi305 edu microscope. Photo 1 is a small version of the full scan at 8x. The original full scan is 22,000x 18,000 pixels. Photo 2 is of a small section at 20x. Photo 3 is the same area at 40x. The maximum magnification of the microscope.

Although this is the same thin section of Rugose Coral posted earlier, they are substantially different in what has been revealed with further polishing. The original thin section was approx. 80microns thin. The additional polishing with 1200 and 2000 grit diamond disks has proved to reveal additional and unexpected detail at a thickness of 35 microns. The new slide photos were taken with a Canon 100D on a Zeiss 305edu microscope. Slide 1 is the cross section as previously posted. Hints of what lay hidden are visible, but the slide is too thick to see detail. Slide 2 is the thin section after another hour of polishing. There are some disc lines in the slide, but I was at the limit of my set up and feared polishing the specimen to oblivion. Slide 3 is viewed through a Dark Field stop. Slide 4 is a close look at the centre of the coral.

or A small Dinosaur, bone. The following are microscope photos of three sections of a small piece of Dinosaur bone. The thin section slides were made using a Hi-Tech Diamond flat lap grinding machine. The first photo is the actual bone segment, approximately 22mm long and 12mm in cross section. The next three photos are full scans of the three cross section followed by a few selected sections. I used two microscopes, a Labomed LB-592 Polarizing and a Zeiss Stemi 305edu with a homemade polarizing kit. Additional Dinosaur bone images Crossed Polars Stage was rotated 45° Plane light, stereo microscope Same section with the Darkfield stop in place.

Thin sections made from Rugose Coral sent to me by forum member CanadaWest.. There are seven corals in this collection. The thin sections were photographed using a polarizing microscope or a stereo microscope with a simple polarizing kit. I was not successful in making good thin section from all of the specimens so some photos are not the best possible. This post is in four parts. Part 1 Coral 2 Rugose Coral, Carboniferous, Livingston form., Invemere, BC Photo 2 - The initial polishing of a transverse section did not look promising, but a detail (Photo 3) looked interesting Photo 4 is the same transverse section with further polishing and photographed with a stereo microscope with the Darkfield stop in place. Photo 5 is a detail at 15x magnification with crossed polars only. The Rugose Corals are also presented as web slide shows.

I received several small Rugose Coral from member Herb to make microscope thin sections.. This is the first completed slide. There should be at least six or seven more slides in the collection. This slide is from the Pennsylvanian formation in Mineral Wells TX, USA Geologic age: Phanerozoic | Paleozoic There were six fossils in this group. The largest is the subject of this post. This is a slice of the specimen through the centre. This shows the cell structure of the Rugose Coral and the minerals that replaced the soft part of the Coral. A web version of this post may be found here.