SM33 Sutters' Mill Meteorite found by observer (broke up over our heads so we hear it and saw the trail) of fall on day 6 of hunt.
One of ten my group found.
The Sutter's Mill meteorite is a carbonaceous chondrite which entered the Earth's atmosphere and broke up at about 07:51 Pacific time on April 22, 2012. The name comes from the Sutter's Mill, the California Gold Rush site, near which some pieces were recovered. This was the largest meteoroid impact over land since asteroid 2008 TC3. Meteor astronomer Peter Jenniskens assigned SM numbers to each meteorite, with the documented find location preserving information about where a given meteorite was located in the impacting meteoroid. As of May 2014, 79 fragments have been publicly documented with a find location. The largest (SM53) weighs 205 grams, and the second largest (SM50) weighs 42 grams.
The meteorite was found to contain some of the oldest material in the solar system. Two 10-micron diamond grains (xenoliths) were found in the meteorite recovered before the rain fell. In primitive meteorites like Sutter's Mill, some grains survived from what existed in the cloud of gas, dust and ice that formed the solar system.
The meteoroid entered at a record speed of 28.6 ± 0.7 km/s, the fastest fireball on record from which meteorites were later recovered. It broke apart at an altitude of 48 km, the highest breakup event on record resulting in meteorites on the ground.
Before entry, the meteoroid moved on an eccentric orbit, stretching from just inside the orbit of Jupiter to the orbit of Mercury. The orbit had a shallow inclination and an orbital period suggesting that this meteoroid originated in the 3:1 mean motion resonance with Jupiter. The CM chondrite Maribo moved on a similar orbit, but rotated by 120 degrees in the direction of the line of apsides. The asteroid family that is the source region of CM chondrite-type meteorites is now thought to be located close to the 3:1 mean motion resonance, in low-inclined orbits, and may be the Eulalia asteroid family.
The meteorite type is similar to that of the 1969 Murchison meteorite in Australia. Unlike Muchison, Sutter's Mill shows clear brecciation: fragments of CM lithologies with different aqueous alteration and thermal processing histories are embedded in a fine grained CM matrix material. The Sutter's Mill meteorite originated from near the surface of its parent body. As a whole, Sutter's Mill is harder than Murchison.
The pre-rain collected meteorite SM2 was found to contain the mineral oldhamite (CaS), a mineral that reacts readily with water vapor. This xenolithic material may have come from enstatite chondrites impacting on the surface of the CM chondrite parent body in the past.
The Sutter's Mill meteorite is used to test sample collection and analysis procedures for NASA's OSIRIS-REx sample return mission.