An Article In Meteorite-Times Magazine
by Tom Phillips and Norbert Classen
NWA 4898 Unbrecciated Lunar Mare Basalt
I often get fired up over some of the microscope
shots but this month the star of the show is Norbert Classen's photo
of his slice.
Feast your eyes on this!!!
This is Norbert's description of the sample in his collection.
"NWA 4898 is a very unusual unbrecciated lunar
mare basalt. It is compositionally distinct from all Apollo and Luna
samples, and it's also unique among lunar meteorites - no wonder
that it first puzzled the classifying scientists who first thought
it to be an angrite until they found out that it's actually a
high-alumina mare basalt. NWA 4898 exhibits a spherulitic texture of
dominantly lath-shaped plagioclase, pyroxene, and skeletal ilmenite.
Olivine occurs as single larger crystals often containing Ti-rich
chromite inclusions. Plagioclase is Ca-rich and has been completely
transformed into maskelynite during shock metamorphism; pyroxene is
compositionally zoned Ti-rich pigeonite and augite. Minor phases
include FeNi-metal and troilite.
My own collection sample is a neat 1.359g partially crusted slice with dimensions of about 20 x 12 x 1.5 mm, showing the unique spherulitic texture and fantastic shock veins throughout the specimen. Given the fact that NWA 4898 consisted of one single stone with a low TKW of just 137g I'm very happy to have about 1% of this lunar meteorite as a reference sample in my collection. What a beauty! "
I must agree, What a beauty! Also a beauty is Jeff Hodges thin section on NWA 4898. With out Jeff's generous loans of extremely high quality thin sections of some of the newest and coolest material known to man, none of my photos would be possible.
This is Jeff's thin.
This one is close up with a polarizer and wave plate but no microscope.
These shots were taken in fully cross polarized light with the addition of a 1/4 wave retardation filter and a Field of View (FOV) of 0.95 mm. The crystal structure is beautiful.
Getting a little closer with a FOV of 0.62 mm.
Now at FOV 0.40 mm.
Finishing with a FOV of 0.25 mm which is an (at the eyepiece) magnification of 400X.
Once again, there is a lot of glass in this one making the use of wave plates necessary for light balance.
This gets me to some thing exciting.
My articles have become better suited to my Meteorite Micrograph Gallery hosted by Meteorite-Times. It started out by me witting an article or two in an attempt to explain what I was doing and how it all worked but it has turned into just me sharing shots of new materials. This is better handled in my Gallery.
You all know John Kashuba. He is an excellent microscopest and an occasional contributor to my articles in images, text and thin sections. He has been a true friend. Our styles are different as I am always ignoring all the rules chasing the perfect image, while he is more true to the science and the "proper way" of doing things. He also has much more knowledge of meteorites than I do.
He is going to be taking over Micro Visions. I look forward to his articles and hope that you all give him a frequent email of thanks. ( After all, that is the only reason any of us write articles for Meteorite-Times.)
I will still borrow the latest cool thin sections from Jeff (If still welcomed to) and make updates to my Gallery. Jeff is also an excellent microscopest and has an image Gallery at http://www.meteoritethinsectiongallery.com/ Maybe John can get Jeff to write a Guest Micro Vision article!
As you may of guessed, Jeff, John and I are good friends and eagerly await news of new thin sections or a shot that turned out soooo good we just had to show off.
Thanks again to Paul, Jeff, Norbert and John for all their help in making my articles as interesting as they could be.
Be sure to visit Norbert Classen's site at:
Tom Phillips can be reached by email at:
The Tom Phillips Microscopic Meteorite Photography and Gallery