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Two specimens: the siderite is 1303 grams, 295 x 270 x 4 mm. the pallasite is 80.7 grams, 95 x 74 x 3 mm   Pallasite, PMG-an

TKW 148 kg. Fall not observed. Found 1884, Santa Fe County, New Mexico, US.


Steve writes:

Photos:

1 - Glorieta Mountain Siderite
2 - Glorieta Mountain Siderite
3 - Glorieta Mountain Siderite Inclusions (montage 1)
4 - Glorieta Mountain Siderite Inclusions (montage 2)
5 - Glorieta Mountain Pallasite
6 - Glorieta Mountain Pallasite Backlit Animation

Glorieta Mountain is an anomalous stony-iron pallasite discovered in Santa Fe County, New Mexico on August 9, 1884. New York mineralogist Charles Sponsler originally found three large masses – 67 kg, 52 kg, and 24 kg – on a rock ledge at the Roival ranch near Canoncito, five miles from the Glorieta Mountain summit and three and a half miles from the Glorieta Post Office. These three pieces were later described in the September 1885 American Journal of Science by Dr. G.F. Kunz, another New York mineralogist and a Tiffany & Company gem consultant who, not surprisingly, was particularly interested in the translucent pallasitic inclusions within the largest mass. A year later, three additional masses were found over a six week period by J. H. Butlock¹.

Dr. Harvey H. Nininger was also interested in Glorieta Mountain, and during his 1937 and 1938 field work there he acquired several pieces of the meteorite that to him suggested the original meteor had fragmented in midair. Fifty-five years later in the same journal as Kunz, Nininger published his opinion that Sponsler’s three pieces comprised the main siderite mass while the main pallasite mass had yet to be discovered.

Then in 1965, Nininger befriended a boy named Steve Schoner who had attended one of Nininger’s meteorite lectures at La Verne College in California. Nininger regaled Schoner with tales of the Glorieta Mountain meteorite, convincing the teenager that more was to be found. Schoner's subsequent recovery of tiny pallasite fragments confirmed in his mind Nininger’s prior claim of the missing main mass. Schoner refused to give up, and fifteen years and seventy trips later – almost a full century after Sponsler’s original find – Schoner's efforts finally paid off when he came across a 20.2 kg pallasitic mass. Before that time the largest Glorieta Mountain pallasite fragment weighed only 395 grams; amazingly, it fit like a jigsaw puzzle piece into Schoner’s new discovery.

After cutting and polishing loss, just over 11 kg of Schoner’s original pallasite remained – with fully half of that going to some of the world’s most prominent museums and universities. But many more pieces of both pallasite and siderite material have since been found – some quite large² – bringing Glorieta Mountain’s total mass to well over 400 kg³. Of those pieces, most under 50 grams are pallasites that exhibit at least a little olivine. The bigger pieces split roughly equally between pallasites and siderites, an example of the latter represented by the slice in Photos 1 and 2 that I acquired from Bob Falls three years ago⁴. The metal in Glorieta Mountain is a generally stable medium octahedrite, though this piece did oxidize slightly at a few spots around the edges and last year underwent an additional nitric acid bath in an attempt to better stabilize it. Photos 3 and 4 show a few magnified areas with some interesting features (though the recession seen in the carbon inclusions is not intrinsic to the meteorite but is instead a consequence of the aforementioned stabilization). And while Glorieta Mountain is considered a prehistoric fall, many larger siderite pieces still have fusion crust, regmaglypts, and even flow lines in some cases.

Photo 5 shows a small 80.7 gram pallasite slice that I was able to acquire last year (also from Bob). Photo 6 is an animated gif presenting various non-backlit, backlit, and front-lit views to better show the beauty of Glorieta Mountain’s gem-like olivine crystals⁵. This piece has been acid etched and nicely displays the bands of kamacite and taenite surrounding the olivine crystals.

Pallasites are already an uncommon meteorite classification, and Glorieta Mountain is chemically and morphologically anomalous and not felt to be part of the main group. Consequently it’s not just historically fascinating but also scientifically unusual, which for me makes it one of the more interesting examples of this class of meteorites.

Footnotes:

¹ An unnamed individual was reported to have found a seventh mass, but it later disappeared before it could be studied.

² As an example, refer to Robert Ward’s spectacular finds posted on 9/4/2012.

³ Glorieta Mountain meteorites can be difficult to find as the strewn field is located in an extremely rugged region of New Mexico that is crisscrossed with heavily wooded mountains, canyons, and deep ravines. An interesting historical note is that part of its strewn field lies on the location of an 1862 Civil War battle, and consequently meteorite hunters using metal detectors have found pieces of the meteorite among such civil war relics as musket balls, buttons, and knives.

⁴ Sorry for the photo duplication, but it was too snowy and cold to take pictures outside, and because of reflections and shadows from shooting indoors, I needed two shots at different angles and with different lighting to fairly capture all of the surface’s Widmanstӓtten patterns.

⁵ For those so inclined, there are easily obtained LED arrays that fit nicely into the backs of smaller Riker mounts (or they can be set side by side for larger ones). These arrays can be attached with doubled sided foam tape and powered by any 9v to 12v power adapter (for the electronic hobbyists out there, you can also make a simple five dollar 555-based timer circuit that will alternately turn the LEDs on and off at a slow rate to basically achieve an effect similar to that seen in Photo 6). A layer of fiberfill between the LEDs and a pallasite slice will nicely diffuse the light, and if desired, translucent milky plastic sheets are available from many craft stores that can further soften the backlighting when placed directly over the LEDs. Finally, a dark cardboard matte cut slightly larger than the outline of the slice will block extraneous backlighting and provide a nice finishing touch. This kind of display also works well for other translucent meteorites, such as thinly sliced diogenites.