An Article In Meteorite-Times Magazine
by Tom Phillips
The King Kapoeta Slide
Kapoeta Howardite: I have never before had the opportunity to work with such a significant thin section. Meteorite magazine did an article that featured this stone in May 2001. The stone is an unusual example with 3 lithologys. It belonged to Dr. King and has become a well known meteorite. As you might imagine, I was nervous putting it on the microscope. It has been many years since I crashed an objective through a slide but this slide was not replaceable (Made out of 100% pure unobtainium)!
The best part of imaging this particular thin section was working with John Kasuba and Jeff Hodges. The thin section belongs to Jeff and he shares his story of how he came to own such a rare piece.
John produced a wonderful cross polarized light image of the whole slide showing the 3 lithologys. I have taken many Xpol micrographs and I know what I am saying when I say this is a fantastic treat for meteorite enthusiasts. You might think that micrographs are easier to produce at low magnification. Nothing could be more wrong. Sure it gets tougher as you go to higher magnification but the real low magnification shots are much more difficult to do well (down right HARD)! Very few people can take a shot like this and John deserves our compliments.
Enjoy this micrograph! John then explains what is going on in the image.
Slide provided by: Jeff Hodges - Image Copyright: John Kasuba
Click For Full Size Image 460K
The left two thirds of this thin section is dominated by what Aurora Pun et al. and O. Richard Norton have referred to as clast H. The fine grained brown area centered on the left edge of this slide is the center of the clast. It is strongly shocked diogenitic material that might have been excavated from the bottom of an impact crater. Surrounding this core is typical howardite – a mixture of diogenite and eucrite set in a matrix that is so finely grained that it scatters light and appears black. A close search of this and other Kapoeta howardite fields might find howardite clasts of different textures that have been incorporated during the regolith formation – breccias in breccia. Beyond this howardite material is a distinctive band of solidified impact melt. This extends from the bottom left of the sample, curving toward the center and widening as it reaches the top. The needle-like crystals are pyroxene and lie in a microcrystalline matrix. At the top of the slide and even further from the center of the clast is another very dark solidified melt. Here the matrix contains pyroxene grains that are aligned in some areas indicating past flow. The remainder of the thin section is howardite.
I have been amazed at Jeff's thin section collection. I often wonder if there is any thing he does not have. It is truly institutional in size and he is an absolute perfectionist. He has most of his slides made for him by the best in the business and every one of the many slides he has let me examine has been a joy on the microscope. This is Jeff's story of how he got the King Kapoeta.
"How I came to possess the Kapoeta Slide from Dr. Kings material"
In 1997 or 98, I had just begun to discover and explore the completely fascinating new world of Meteorites in thin sections when I sought out and made contact with "The Best" thin section maker in the World. I wanted him to custom make my slides. Luckily for me the two of us hit it off pretty good and we quickly became good friends and still work closely together to this day.
About this same point in time I decided to go visit John Sinclair, an old and well known name in the meteorite dealer community. I would occasionally go by his house to visit with him and purchase meteorites. That afternoon we were going through some of his inventory looking for interesting items to add to my growing meteorite collection when he pulled out an epoxy "core" with a thin slice of Kapoeta embedded in it for producing thin sections. He explained that he had the winning bid when the piece was auctioned off from Dr. King's collection. I was impressed. He also won a Kapoeta Thin Section from Dr. King's collection. I remember that it was very beautifully but I can't recall if it shared the same special characteristics as the piece still in the epoxy. I believe he paid about $300 for the thin section but I don't remember how much he paid for the core. It had no other special markings or specimen #'s that I can recall.
Well, I loved his Kapoeta slide so much I asked if we could send the core off to my new thin section making source to give him a try. I was however already familiar with the quality of his work as most of my thin section collection at the time (96 out of 98 slides) were made by him. John agreed and about 2 months later we each had a new "King Kapoeta Slide". Neither one of us had any idea as to the true significance of the specimen at the time though.
I held on to my slide but I believe John sold his slide(s) but I have no idea where any of them ended up.
It was not even two years ago that I finally discovered how special these slides really are. I had posted a few photos taken through my microscope in my first attempt at microscopy. One was a photo of the Kapoeta with a comment that it was an important specimen from the King Collection but did not go into any more detail than that.
I think it was a prominent List Member who replied to the list with a comment affirming my statement and also, to my surprise a few links to an important article written about the "King Kapoeta Sample" with 3 lithology's etc. Boy was I thrilled! I have at least 3 other Kapoeta slides and they are all very nice sections. But, none of them contain anything close to what Dr. King's oddball piece has to offer.
These micrographs were taken in cross polarized light with the addition of a 1/4 wave retardation filter. With a sample known for it's multiple lithology it seems kind of dumb to take such high magnification shots. Oh well, it's what I do. I hope you enjoy them.
These four were taken at a magnification of 160X.
These six were taken at a magnification of 400X
And finally, (I had to give it a try) these two were taken at a magnification of 700X.
Tom Phillips can be reached by email at:
The Tom Phillips Microscopic Meteorite Photography and Gallery