Over the years I have written about cutting meteorites many times. I have not written about the challenges of cutting tektites. So I will venture into that area this month. I may attempt to cut one some time soon for a little research project Paul and I are working on..
First let me say that for the amateur with a diamond saw it will always be a crap shoot cutting splashform tektites. There is always a probability that they will fly apart into many pieces. Why, some of you may ask. Tektites are made of glass as we all know. But, they are made of glass that is formed from a plastic lump that cooled very fast and without uniformity. They cooled on the outside while the inside was still hot. There were forces exerted on them changing their shape while they were cooling. All this causes the glass to be highly stressed. So sometimes when you cut one everything will be going swimmingly for a while and then POW. You will have a little cloud of fragments cascading about the saw. But, like I said it is a crap shoot on other occasions you can cut thin slice after thin slice with no problems at all. I recommend however, that anyone cutting tektites use eye protection in the form of a full face shield. Glass slivers are nothing to mess around with.
Remember I said all the previous was the common experience of amateurs cutting tektites. In a laboratory setting the tektites would be annealed in a furnace to remove the stress and reduce the danger of their destruction by cutting. It happens that I have a furnace which reaches high enough temperature to anneal glass. But, it is not programmable for slowly cooling. So for me I take the same risks as other amateurs when cutting these little glass enigmas.
Over the last decade or so I have cut tektites from Thailand, the Philippines, China, and elsewhere. I have cut australite buttons into thin slices and mounted them on slides. I have produced beautiful slices of moldavite mounted on slides. LDG and impact glasses have found their way into my saw. Most have been successfully cut and the slices polished and sold. But, occasionally a tektite will come unwound in an instant and scare the day lights out of me for a second. There is never any warning it just happens.
In another life, when I was really young I dreamed of pursuing archeology as a career. I spent some time in Mexico mostly driving equipment down for the University but some time worked at digs. Obsidian was used to make wonderful blades there by blasting long shaped flakes from prepared cores. They told us that the shock wave removed the blades from the cores in 1/1250th of a second. I can attest to the fact that the disintegration of a tektite is very similar in time frame. It is instantaneous and fascinating. I always wish that I had a camera that could record the shattering event. There is a strange sound a kind of a pop but not really, a kind of a rip but again not really.
When the cutting goes well you will have a thin slice that once polished will show the schlieren in the glass. Schlieren are the lines that demark the folds, twists, and zones in the tektite glass. When viewed under a microscope with angled lighting they appear as dark lines. They have a fluidal quality that unmistakable.
There is a lot that can be learned by cutting various tektites and impact glasses. For example the lines in LDG are straight and not twisted as in splashform tektites. Perhaps an indication that them material never flew. Moldavites on the other hand have the most intricate shclieren I have ever seen. An I would have to say the most stress. On several occasions I have cut moldavites into slices and polished those slices on both sides, only to have them hours later crack while sitting next to me on the table. It is funny how they will stand the forces of cutting and polishing but later stabilize themselves cracking to relieve stress.
For you viewing enjoyment I have included here at the end a photograph of a one millimeter thick slice specially illuminated to show the 3 dimensional nature of the internal structure of tektite glass.