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Sioux County

Sioux County is an achondrite (eucrite-mmict) that fell in Nebraska August 8th, 1933. 

The meteorite’s fall to Earth was well-recorded as it was mistaken for an earthquake by some, and written up in local newspapers. Photo copyright CMS/ASU Photo copyright CMS/ASU

This article first appeared on page 5 of the Lincoln Star (Lincoln, Nebraska), Thursday, August 10, 1933:

Report Meteor Buried in Field Near Alliance
ALLIANCE, Neb., Aug. 10 – (AP) The spot where a huge meteor which shook western Nebraska and eastern Wyoming Tuesday landed, was believed located yesterday about 35 northwest of here.
First reports said the meteor buried itself in a field, leaving a hole 25 feet or more across.
The meteor was seen by many persons in western Nebraska as it streaked northward across the sky leaving a long trailing plume of white smoke.
Persons 20 miles north of here saw the meteor apparently explode almost directly west of them with the largest mass of it falling to earth.
To those watchers came a booming roar almost three minutes later. The roar lasted about 30 seconds, a farmer, N.B. Jacobson, who heard it from the field said.
Calls were received here from as far away as Scottsbluff, where the meteor also was seen, asking where the giant explosion was. Telephone lines were busy long after the report as people believed an earthquake or great explosion had occurred. Dishes and windows in homes 15 to 20 miles away were rattled by the concussion.

Eucrites are the most common type of achondrite meteorite falls (vs. finds) and are believed to have formed from the cooling of magma on the surface of the Asteroid 4-Vesta; the number 4 refers to Vesta being the fourth asteroid ever discovered, in March of 1807, by German astronomer Heinrich Wilhelm Olbers.

In September 2007, NASA launched the Dawn mission to study Vesta and the dwarf planet Ceres to provide insight into the formation and evolution of solid bodies in the early solar system, using a visible camera, a visible and infrared mapping spectrometer, and a gamma ray and neutron spectrometer. Dawn stayed in orbit around Vesta for a year, thoroughly studying the asteroid's geology, chemistry and more; insights gained there helped build the link between Vesta and the howardite-eucrite-diogenite (HED) class of meteorites.