An Article In Meteorite-Times Magazine
by Tom Phillips
NWA 960 Very Rare Anomalous Chondrite
It's not to often I see things in meteorites that leave me saying "Wow, I've never seen that before". This meteorite did just that.
Jeff Hodges has a huge collection of thin sections. He should post the catalog, and you would say "Wow, I've never seen that before". He is letting me examine them to produce images for the Gallery. He is even having thins custom made to 1/4 micron polish (both sides) uncovered just to suit my imaging techniques. This rare thin is one of his. If you know Jeff, give him a thanks and let him know you saw his thins. We all like to know our efforts are noticed.
Greg and Adam Hupe brought this meteorite to us and Adam wrote this interesting description that I was permitted to steel.
If any one has a thick sample they are willing to lend I would welcome the chance to put a 1/4 micron polish on it and get some great incident light shots. I would of course return it (reluctantly).
This is Adam's write up on the material.
NWA 960 Very Rare Anomalous Chondrite
THE TOOTH STONE
NWA 960 (Provisional), an acutely rare and Anomalous Type 3, S1, W1-2, Fa9.3 Chondrite found in the Sahara desert in 2001. We nicknamed this meteorite "The Tooth Stone" because it was like pulling a tooth getting it classified, taking well over 5 years, the longest in our history. Every time we inquired about it over the years, we were told that it was escalated to the next level. The classification of this meteorite was no easy task with six heavyweight laboratories involved with bringing its classification to a conclusion. NASA, JSC, UC, UW, NAU and Carnegie Laboratories all contributed to the data and concluded that it is Anomalous, meaning it is like nothing they had ever seen or understood before. Although the D17O values are near those for H chondrites, the d18O values are much higher, and the mineralogy of this specimen is very different from that of H chondrites. An extreme oddity is that absolutely no metal was found in this meteorite, even at the microprobe level. A Total Known Weight (TKW) of 997 grams is recorded for exceptional find.
From a visual standpoint, this is a very pleasing looking chondrite with crisp wall-to-wall chondrules. There are so many multicolored chondrules that we don't think that there is any room left for a matrix. Maybe, you could call the inexplicable sparse black clasts the matrix but only a few were found. Anyway you look it; nothing like this has ever been encountered before. There is a lot of behind-the-scenes interest in this meteorite so you may wan to pick up a piece of "The Tooth Stone" while these large specimens are available. It is certainly priced very reasonably considering it is a one-of-a-kind and a lot of resources were put into it.
These first micrographs were taken on an aus Jena Fluoval in cross polarized transmitted light with the addition of a 1/4 wave retardation filter (to draw out more color contrast).
Once again, necessity drives experimentation. The thin section is covered and I am dying to do some reflected light examination. This is what I came up with. Please keep in mind, I do not think I found a method useful in classification, just a cool way to look covered thin sections.
These were taken in incident (reflected) cross polarized light on an aus Jena Neophot at a magnification of 345X. I had to control the glare off the cover slip. I did this with 2 polarizers and one analyzer polarizer. I needed A LOT of light so I used the Xenon lamp. I also had to fight glare by reducing the aperture and field diaphragm to extreme minimum. The aperture was not much more than a pin hole.
The results were interesting. Let me know what you think. I would rather have a polished thick slice but these will have to make do until I come up with one.
Tom Phillips can be reached by email at:
The Tom Phillips Microscopic Meteorite Photography and Gallery