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Thin section between crossed polarizers.   H5

TKW 4 tons. Observed fall 8 March 1976, northern part of the district of Kirin, Kirin Province, China.

 

Steve writes:

The Jilin meteorite fell at around 3:00 PM local time on March 8, 1976. Residents in the Kirin Province’s northern town of Hsinglung, China witnessed a red fireball moving for 300 to 400 km in a southwest direction across the sky (Kirin is also known as Jilin, the latter being the meteorite’s namesake). The fireball was accompanied by a deafening roar, several explosions, and three distinct fireballs. Despite the tremendous shock waves from the event that broke many windows, no injuries were reported (the explosion measured 1.7 on the Richter scale). Still, many superstitious people considered the meteorite to be a bad omen, a belief reinforced by the death of Communist leader Mao Zedong just a few months later.

The Jilin meteorite was a massive meteorite fall, with more than a hundred fragments showering a 500 square kilometer area. The largest piece hit only a couple of hundred meters from a nearby house, producing an impact pit six meters deep and raising a mushroom cloud 50 meters high. At 1170 kg, it was the largest single fragment of a stony meteorite ever found.

Jilin is an H5 stone olivine bronzite chondrite meteorite thought to have been ejected from the asteroid belt some 8 million years ago, with the last thermal event happening about 33,000 years before it fell (a half kilo piece currently for sale claims a rare shatter cone structure that only forms at pressures of 2 to 30 gigapascals). Jilin is purported to contain 18 chemical compounds, as well as the amino acids oxyproline, aminoacetic acid, alanine, serine, and amino isovaleric acid.

In this post, I offer an xpol thin section view of Jilin. Because type 5 ordinary chondrite meteorites have been thermally metamorphosed and recrystallized, most chondrules are no longer distinct. Photo 1 shows the entire slide, which can be zoomed in here:

Jilin H5 Chondrite Meteorite Thin Section (Xpol) (gigapan.com)

As a reminder, click on the diagonal arrows to the right of the image to go full screen, then use the mouse and its scroll wheel to zoom in and out and pan around.

Some of the most interesting areas of this thin section can be seen in Photos 2 through 5.