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Fifty Years of Cutting Meteorites

It has been a long time since I did an article on cutting meteorites but since that is mostly all I am doing right now it’s what I have on my mind.

At certain times of the year as necessity demands, I spend weeks in the lab cutting stones to resupply our catalog. We get a few new stones every year too that I cut, but often I will pull out a stone that I have cut on before and continue taking more slices off. I have sealed containers with desiccant going back many years. I get requests from Paul for more slices or windowed stones of several items and work usually about six hours a day until the pieces are done. It is all pretty routine now after 50 years of cutting both rocks and meteorites. But I remember how it was in the beginning when I was just a kid in my twenties doing lapidary as a portion of my multi-faceted income stream. In those days it was mostly rocks made into gemstones for the jewelry I created to sell at the artist faire on the weekends. But I was collecting a few meteorites even then and had been since I was 14 and visited Meteor Crater. I did not have the money to buy very many. I had made a little saw out of a motor and some pulleys. It used a tiny thin 4-inch opal cutting blade. This claptrap machine worked pretty well and I could have it at my apartment to use at night after my other jobs. I was using sandpaper stuck down to a thick piece of hard plastic and a hand cabochon maker for doing the gemstones. I was on the outs with my parents at this time and had no access to the nice Highland Park combo saw, grinder and polisher over at their house. I had used that machine since I was 12 years old. I still have that Highland Park machine though I have not yet reinstalled it at the new house. But I made the hand operation work and I just needed to make a few pieces a week to have for the weekend. I did the silver work in the apartment too. I used an alcohol lamp with a blowpipe for the silver soldering. Somehow the word got around that I could cut stones and a couple of the meteorite dealers asked me to cut meteorites for them. I took payment in pieces of the stones so I was able to slowly add to my collection without spending any dollars. Rolling time forward a few years I am no longer quite so broke and can do more. I added a homemade lap to the inventory and a homemade polisher. I upgraded to a much better homemade saw that took a 6-inch blade and was much more flexible to work with. I had a place to use the real silversmithing tools that I could not use in an apartment. Things such as my acetylene torch and Foredom handtool. I was doing much more jewelry and cutting more meteorites. I was cutting at least a couple of stones a week for others by this time. Usually, it was just a split down the middle with polishing the faces of the halves but occasionally it was to slice a stone completely up. Last year at Tucson I saw one of these stones in a display case in a dealer’s room. It was half of a Millbillillie and I recognized the old friend instantly as one I cut over thirty-years ago. Funny how sometimes the meteorites just make the rounds from one person to another over the decades and they come back to be seen again.

This is an image of the homemade polisher I made about fifty years ago. I got a double electric blower from a junker and cut off the shrouds turning them into shields. For a couple of dollars each I got the buffer spindles and attached them to the shafts I removed the actual fan blades from and then added two buffing wheels. I wired it up with a switch and cord. I still use this for polishing silver work.

Today I have commercial equipment except for the main saw I use most of the time. It is special and there is nothing as nice on the market. It has dial micrometer adjustments for setting the thickness of slices and a digital stepper motor feed control, recirculating pump and spray jets to direct the cooling water onto the front and sides of the blade. It takes both 6 and 8-inch blades. I turn it on and go do something else while it cuts.

https://youtu.be/EbpcIVzhGBI

I can make over a hundred cuts a day on the saw if the stones are small. Each cut can be as thin or thick as I want and each can be the same as the rest in a batch with exactness so close you can not feel the difference in thickness if they are laid next to each other on a table. After thirty years of saw designing, I am really happy with this one. The laps are now nice purchased machines. I retired the homemade one when the motor bearings finally got terribly wobbly after twenty-five years. I have a complete lab today with almost everything one could want and when something new is needed I can just buy it nowadays.

But I have not forgotten those years in the past when times were lean. I had a fear-induced healthy respect for the meteorites back then. I needed to cut them correctly and make no mistakes because I had no money to replace a wrecked stone or a wasted slice. Richard Norton had come out with the first edition of Rocks From Space sometime in this period and made a point that wedged slices were useless and the worst thing there was. So I was not going to make those if I could help it.

This is a finished batch of Lunar NWA11474 that I cut just about as this issue was being put together. It was a much smaller stone them some I have cut, still, the full slices shown are about two inches on the sides. Much larger than the tiny pieces of the Moon we once bought. It was a stone with plenty of fractures in places so I have ample small and tiny pieces for our catalog. The slices were finished through several diamond lapping disks to 1200 grit and then polished on a felt disk with 100,000 mesh diamond powder. Everything is saved with lunar meteorites. I cleaned the saw before cutting anything else so the collected moon dust would be pure lunar.
Some of the very exotic meteorites of today are cut quite thinly to offer the best price and lowest weight for the biggest surface area. With slices that are so thin, it requires great care to keep from breaking the pieces in the saw. If my saw did not run smoothly it would be impossible to get the slices as thin as what this image shows of a full slice of NWA11474 Lunar in calipers. The dial reads 0.060 of an inch or 1.524 millimeters.

I took the trouble from the very start decades ago to make sure the stones were never exposed to anything that would contaminate them. That is why that old half stone I saw in Tucson still looked good I guess. I still just use distilled water and still soak all the slices in alcohol between stages of work and polish with just diamond, not any other polishes. It is not any more costly and a lot less trouble to polish with diamond. With diamond paste, you seldom recharge the felt disk and it lasts a long time so you use very little.

I always sat down with the stones and sort of introduced myself to them. I examined them for cracks and flaws so I would not get into trouble later and drew lines with chalk on the stones for where I would make my cuts. On bigger stones, I still do that today. I even ask for chalk lines from the two or three people I continue to cut for. I am not taking any new clients or work. But have three friends that I buy and divide meteorites with. The stones are ones we like and want to get classified. We split the cost to buy the stones. I cut off the type specimen and prepare it so it looks good for the lab doing the classification. Then we sit back and wait for the results a few months later. We almost always have something in the works and I feel great to be adding to the knowledge base by sending cool meteorites off to become official. I cut the stones in half usually and send the partnering friend his piece. It always makes for a period of conversation and texting. I would only see or talk to these friends at Tuscon without this extra fun meteorite sharing.

Twice in 2018 I had stones sent to me by friends that told me what the stones were supposed to be only to find after making the first cut that they were something different. One turned out to look like an R Chondrite. So I stopped cutting the slices off and contacted the friend. It was classified as an R3. Very Cool. The other was equally exciting and a nice surprise for that friend. As many have said visual pairing is just not a thing to try and do. It is a snare that responsible meteorite people should never fall into. I have had fun guessing what a stone is as I send it off to be classified. But it is just a fun activity within my mind or a small circle of friends. I have sent off meteorites that I was quite sure would make the cut as type 3 chondrites only to have them turn out as type 4. Many times I thought two stones from a box batch would be the same from their outside appearance only to find when they were cut that they were quite different. They had fooled someone else before me too. I have a pile of stones that I sorted out from big batches of NWA 869 that I know are not NWA 869. The truth is only revealed by the saw and the laboratory. Field handling of stones is not always as good as it might be and mixing occurs as the stones pass through many hands. This is not much of a problem when the stones are being sold as unclassified ordinary chondrites. If one turns out to be something much nicer no one is complaining. But when it is something unusual like a Lodranite or Acapulcoite or Brachinite then the care in handling is critical and the differences visually are more difficult to see in a small hand specimen.

I try hard to be meticulous about labeling and bagging of specimens as they are handled in my little lab. This week I had 14 different meteorites being worked on at the same time. I will cut for two or three days and then lap and polish for several days until they are all finished. I cut off what I need from one and pack up the surplus, reweighing it for the inventory; writing the weight on the container. I bag the slices or fragments until it is their turn to be worked on again writing the meteorite name on the bag and often including a slip with the name into the bag just for safety. Sometimes the ink on the baggies gets rubbed off a little. Then I take the next meteorite and prepare it for cutting and do the same with its pieces. Lapping and polishing are done on just one meteorite name at a time. I don’t make piles or put them in compartment boxes or any of that kind of thing. Piles get bumped and boxes get dumped and meteorites would get mixed. Today I worked on NWA7678, NWA 7454, and NWA4502. They are all Carbonaceous Chondrites. Visually I can tell the NWA4502 from the other two but only clues from the cutting like the shape of slices could be safely used to distinguish the NWA7678 and NWA7454 they are pretty darn similar. It only takes a moment extra to do it in my obsessive way. Today it is hard to even know if the meteorites are different. So many end up being classified multiple times and getting different numbers.

But regardless of how careful you are things happen. We buy stones at gem shows and they are classified and numbered and everything is supposed to be fine and about once a decade I will find a stone in a batch that like the NWA 869s does not match the rest. It goes off to the nice, but unknown stone pile to be sold without pedigree. Paul and I would rather do that than have someone find something funny later about one of our pieces.

It seems to be pretty common for individuals who become interested in meteorite collecting to decide that they also want to begin cutting them. I see posts quite regularly online from new collectors who are now new cutters. Meteorites are not like regular rocks in any way. It is far more than just their point of origin beyond the Earth that distinguishes them as different. They need to be prepared by special techniques using the correct materials or they will be nothing more than a pile of brown goo in a few years. I have had nothing but fun cutting meteorites. It remains far more fun than work even today as I spend much of my retirement working on them. But I have spent 40+ years learning about them, writing about them, and researching them to feel confident that they can survive the abuse I put them through in cutting and finishing them. I would, therefore, encourage anyone jumping into the area of meteorite cutting to do as much learning as they can about how to do the work correctly to maintain the safety of the extraterrestrial material.

Over the years I added thin section making to the list of my preparation skills. I started when I was barely more than a kid making my first thin sections using biology slides that were 1 x 3 inches and which don’t fit my thin section cases of today. I used epoxy from the hardware store which has turned yellow after the decades. I ground the meteorites down on aluminum oxide sandpaper and finished them with the help of a homemade polarized light viewer. I finished them using 1000 grit paper and looking over and over at them in the viewer after ever few strokes across the sandpaper until they showed good interference colors. They were really crude. Well, things have changed a lot with that too over the decades. Now I do them with diamond disks and polish the slices that are full slide coverage instead of tiny chips to a bright polish before mounting that side to the glass. The slices are barely 1 mm thick to start with and when they are finished they are almost as good as a commercial slide. I do them in batch but it averages that I can make one in about an hour. I always make them for a meteorite before sending it off to be classified. This gives me a much better idea of what I am sending away and helps make the waiting months go by easier. About a year ago I had a beautiful stone that I wanted to get classified. It was fresh with a nice matrix and packed with distinct chondrules. I was so delighted with the stone when I cut it that I also cut a thin slice just barely one millimeter thick and made seven thin sections from the slice. While all the thin sections were very good three were superior to the others. I posted on FaceBook some micrographs in polarized light of the meteorite. Shortly after the posting, I was emailed by a friend who is my favorite classifier of meteorites that they would love to classify the stone since it had characteristics they could see in my images that were currently part of a research project at the lab. I eagerly said, “Sure of course.” As time was a consideration since some of the research work was due soon. I offered to send one or two of my self-prepared thin sections so they could save the delay of several weeks in getting their own prepared. My work needed to be repolished with colloidal silica to get rid of the residue from my diamond polishing but my section was used in the classification work. I was just thrilled. That was like coming all the way around from my crap learning experiments of forty years ago to something good enough for laboratory use. I have many stones go through my cutting lab and it is not unusual for me to take a thin slice for thin section preparation. It is always later when I have the time. I think I packed about a dozen mounted slides before we moved and have not gotten the time yet to finish them. But that will make a nice project and give me hours of great photography fun once they are made.

This is an image from NWA11991 showing the clustered chondritic texture that the meteorite has in many places. The photograph was taken from a thin section in the batch of seven I made when the meteorite was first cut.

I have embraced every area of meteorites during my life. They have been a source of knowledge and immense enjoyment. I have merged several other hobbies with the meteorites to enlarge that experience even more. I use appropriately weathered and low-quality stones for jewelry sometimes and tumble the scrap and broken small pieces to enhance them. Paul and I hunt them and find them with friends and by ourselves. I collect them and write about them. I have met fantastic dealers and famous people from all around the world and been on TV talking about meteorites. I give the occasional lecture to groups about them and have cleaned, cut and finished meteorites for some amazing museums and institutions. And of course, made specimens for hundreds of wonderful customers worldwide. I hope the fun will continue. Meteorites are a great hobby and a tremendous opportunity for learning about our solar system. Can meteorites compete against video games and social media for the interest of the next generation? I guess time will tell that. Until the next issue enjoy your space rocks.

Here is part of a batch of cabochons that I made recently to resupply the catalog. Cabochons were one of the first things I made from stone as a 12-year-old kid after my father bought the Highland Park combo unit.
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