A Pair of Oriented “Bakesale Juancheng” Meteorites

In celebration of the publication release of Michael Blood’s new book titled Aspects of Meteorite Orientation I thought I would share a couple oriented specimens I picked up in Tucson years ago. They were part of a set of Juancheng individuals that were collected by school children and later sold as a fundraiser for the school. I sold all of the pieces with documentation as  what I called “Bakesale Juancheng” specimens since they were collected specifically to be resold in Tucson by a Chinese mineral dealer who would carry back the money to the school after the show.

According to the Meteoritical Bulletin…
Juancheng
Shandong Province, China
Fell 1997 February 15, 23:23:35 Beijing time (15:23:35 UT)
Ordinary chondrite (H5)
A shower of small stones (>1000 individuals) fell near the Yellow River after a brilliant fireball with smoke and sparks terminated in a loud, resonating explosion. The fall ellipse measured ~10.5 ´ 4.3 km, oriented east-west. The largest recovered piece weighed 2.7 kg, and the total mass is >100 kg. One fragment was reported to have penetrated a roof and landed in a pot on a stove. This meteorite has been widely traded and sold under the unofficial name Heze. Classification and mineralogy (Chen Yonghen and Wang Daode, GIG; Wang Ruitian, HBS; A. Rubin, UCLA;): olivine, Fa19.0–19.2; pyroxene, Fs16.9Wo0.1; plagioclase heterogeneous, An9–33Ab63–84Or3–12; kamacite contains 0.36–0.47 wt% Co; shock stage S2. Specimens: 35 kg, DPitt; ~1 kg, ZMAO; ~1 kg, BeiAP.

These two oriented specimens are little gems that forever hold the impressive features of hypersonically carved rock that only atmospheric reentry creates. From the tip of the leading face, to the vacuum-formed underbelly, these Juanching jewels are not only collectable meteorites, but also pleasant memories of meteorite adventures.

A classic pincushion shaped oriented stone meteorite. The little bit of cloth tape scars the surface with a weight, but since this “Bakesale” stone carries with it a human story, the tape remains as testament to the students who started this stones earthly journey in the same question most student bake cupcakes and cookies.

 

It’s hard to believe that this side of the specimen is even on the same planet let alone same stone as the traditional oriented shell of the leading edge. Smooth, bubbly abrupt, melted. It is if someone took a knife and sliced the meteorite in half. I suspect there was some upper atmospheric breakage given the harsh 90 degree edges, but there was still plenty of time in the meteorite’s fall to make only primary fusion crust during the fall.

 

This shield shape is another classic form borne out of a fiery arrival to earth. Displacing the intense forces of reentry gravity in the most economical way possible ablates a meteorite into a perfect shape for dissipating energy over the greatest surface area.

 

In addition to the smooth underbelly, a rollover rim is visible where molten rock flowed off the leading surface and wrapped itself under the meteorite being pushed into the low pressure region formed as the stone fell at hypersonic speed without tumbeling.

 

A side view of the rollover rim also shows some rippling as the waves of liquid stone lapped up against the shores of stones sourrounding  the meteorite during the few brief moments before the icy stratosphere forever froze the stone solid preserving the motion as a trace fossil of cosmic physics.

 

 

…Until next time…next year ( ; – }

 

 

About the Author

Martin Horejsi
Dr. Martin Horejsi is a Professor of Instructional Technology and Science Education at The University of Montana. A long-time meteorite collector and writer, before publishing his column The Accretion Desk in The Meteorite Times, he contributed often and wrote the column From The Strewnfields in Meteorite Magazine. Horejsi is currently a monthly columnist in The Science Teacher, a journal by the National Science Teachers Association. Horejsi specializes in the collection and study of historic witnessed fall meteorites with the older, smaller, and rarer the better. Although his meteorite collection once numbered over a thousand pieces with near that many different locations, several large trades and sales have streamlined the collection to about 250 locations with all but 10 being important witnessed falls. Many of the significant specimens in Horejsi's collection are historic witnessed falls that once occupied prominence in the meteorite collections of Robert A. Haag, James Schwade, and Michael Farmer. Other important specimens were acquired through institutional trades including those from The Smithsonian Institution, Arizona State University, and other universities.
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