LINK: Overview of the Hall of Meteorites
Whole Specimens and Thin Sections of Meteorites
Specimens in the Hall of Meteorites

a carbonaceous chondrite, found in McLennon County, Texas in 1943.
This is a good example of a meteorite of the same type as the Allende meteorite which will be featured in the Hall. The round objects which dominate the surface of this cut slab are "chondrules", which formed as free-floating molten rock droplets in the early solar nebula, before they combined with dust and other particles to make these "primitive" meteorites. The chondrites are considered "primitive", that is, basic or primal, because the rock-forming elements in them are present in the same relative proportions as they are in the sun. In fact, if you could cool a piece of the sun so you could hold it in your hand, you would be holding a piece of carbonaceous chondrite, like this one! Some of the chondrules on this surface are discolored by rusting of metal in them, before the meteorite was found.
Bella Roca
an iron. Found in 1888 at Sierra de San Francisco, in Durango, Mexico This is a 'medium octahedrite', with ~0.7mm bands of iron alloy making up the "Widmanstatten pattern". Round nodules of metal sulfide separated from the iron as the iron slowly crystallized into the pattern you see here.
a pallasite. This meteorite was found in 1882 in Kiowa County, Kansas.
THE FARMLAND NEAR BRENHAM, KANSAS, is flat and almost entirely free of rocks—yet farmers in the 1880s occasionally bent their plows on mysterious metallic objects. Homesteader Eliza Kimberly noticed that the odd black rocks resembled a meteorite she had seen as a schoolgirl in Iowa. Despite teasing from her husband and neighbors, she collected a large pile of the "iron rocks", and after five years of letter-writing she convinced a scientist to look at them. They were indeed meteorites.
The remarkable Brenham meteorite fragments contain gemlike olivine crystals embedded in an iron-nickel alloy. Billions of years ago, this rock and iron mixture formed when a large asteroid melted and separated into an iron core and a rocky crust. Meteorites that come from the deep interiors of such asteroids provide tantalizing clues about the interior of Earth and other planets.
The Brenham meteorite scattered about 3-1/2 tons of meteorite fragments in the vicinity of Brenham, Kansas. Pieces of the Brenham meteorite have also been found up to 1,500 kilometers (1,000 miles) away—transported by Native American traders and buried in mounds by the Hopewell people more than 1,500 years ago. Some pieces were pounded into iron knives, ear ornaments, chisels, buttons and beads.
For thousands of years, meteorites were the primary source of iron metal for peoples around the world. All natural iron rusts, or oxidizes. But only meteoritic iron is mixed with nickel, forming a steel alloy that is extremely strong and rust-resistant.
Costilla Peak
an iron. Found in 1881 in Taos County, New Mexico, USA. This is a 'medium octahedrite', with ~1 mm bands of iron alloy, illustrating the "Widmanstatten pattern" common in iron meteorites. This pattern and its details allows scientists to calculate how long these pieces of the cores of early planets cooled. Some cooled as slowly as 1 degree per million years!
Cruz del Aire
an iron. This was found in Mexico in 1911. The pattern of the metal crystals and their balance of iron and nickel tell meteoriticists the rate of cooling of this piece of the core of an ancient early planet which was disrupted by violent collision.
Esquel (high resolution Apple TIF)
a pallasite. There is a slab of this meteorite in the Rose Center Hall of the Universe. Esquel was found in Argentina in 1951. Translucent crystals of olivine, which also makes the gem variety 'peridot', a birthstone, are set in a matrix of iron-nickel metal. Some of the olivine forms large clusters, as seen in upper right.
an iron. Found in 1915 in Portcurtis, Queensland, Australia. This is a 'coarse octahedrite' with bands ~2.8 mm wide. It is from the core of an early differentiated planet, since disrupted by collisions. Large iron-sulfide nodules, found in all iron meteorites, are obvious in this specimen.
a pallasite. Found in 1924 in Australia, Northern Territory. This thick slab has large angular olivine crystals.
a pallasite. Found 1822 in the Atacama Desert of Chile. This is an unususual whole stone showing the natural appearance, unsliced, of a pallasite meteorite. The olivine crystals are luminous, even in this thick specimen.
a diogenite. Fell in Colorado July 6, 1924, 4:20pm. This is probably a sample of the asteroid Vesta, the 4th ever found, (in mid 1800s), and the 2nd largest known. This is a "differentiated" meteorite from the rocky outer region of the asteroid. The green mineral is pyroxene, a common mineral in terrestrial basaltic lavas, and in basalts from other planetary bodies such as Mars. The AMNH will exhibit this sample, which is the "main mass" of Johnstown, meaning that it is the largest of the 27 stones from space, all of which are collectively referred to as "Johnstown".
an ordinary chondrite. Fell in Peekskill, NY, in 1992. On October 9, 1992, a brilliant fireball flashed over Peekskill, New York, startling fans at a high school football game. Nearby residents heard a terrific crash as a rock the size of a bowling ball dropped from the sky onto a parked Chevy Malibu, piercing the trunk and denting the pavement beneath it. Seconds after the crash, the stone was found near the car’s crumpled trunk, still hot and smelling of sulfur.
The Peekskill meteorite made headlines because of the unusual damage it caused, but of greater interest to scientists was its spectacular journey. Thousands spotted the greenish fireball as it streaked across the eastern United States, and more than a dozen witnesses captured it on video. The unusually detailed record of the speed, angle and direction of the falling meteorite enabled scientists to reconstruct its journey through space.
Before they strike Earth, all meteorites orbit the Sun, just as the planets do. The Peekskill meteorite was one of only a handful of meteorites observed closely enough to calculate its entire orbit. Its path has been traced back to the inner edge of the main asteroid belt, between Jupiter and Mars, indicating it came from a main-belt asteroid.
Eighteen-year-old Michelle Knapp of Peekskill, New York, a small city some 50 miles north of the American Museum of Natural History, was home watching television when she heard what sounded like an auto wreck. Stepping outside to investigate, she found a twisted hole in the trunk of her car and a smoking,12-kilogram (27-pound) rock beneath it. Scientists later concluded that the Peekskill meteorite was a fragment of a larger stone, perhaps one to two meters (three to six feet) wide, that broke up in Earth’s atmosphere.
Because of its peculiar fate, Knapp’s car became famous, displayed in Paris, Munich, Tokyo and here as "the car that was hit by a meteorite". Although meteorites fall to Earth every day, such accidents are uncommon. They sometimes hit buildings, and on rare occasion animals or even people, but there are no known cases of a person being struck and killed by a meteorite.

Credit: All whole specimen photographs presented here were taken by Christopher Ebel, a volunteer in the Department of Earth and Planetary Sciences, American Museum of Natural History.

Thin Sections of Meteorites
A suite of images are taken from thin sections, 30 microns (a thin human hair) thick, made from very small pieces of meteorites. One image is of a very round chondrule, about 2.2 millimeters in diameter, in the Allende polished thin section (PTS #4311) that is on display in the Hall of Meteorites. The specimen (4311) from which it is cut is also displayed.
Meteorite PTS look transparent in ordinary (plane polarized) light. These colorful shots are taken in 'cross-polarized' light, through a research microscope. Light goes into the section through a polarizing filter, and is filtered again before the eyepiece. The interaction of mineral crystals with the light causes spectacular colors.

-pc Allende 4311 (dse) chondrule 1
-mac Allende 4311 (dse) chondrule 1
Allende 4320-FTA3 (dse) "fluffy" Ca-, Al-rich inclusion (CAI)
Allende 4884 (dse) Olivine-rich refractory inclusion
Although this object looks like a CAI, it is actually an aggregate of small olivine (Mg2SiO4) crystals.
Allende 4320-FTA4 (dse) Complex assemblage
Here, an irregular CAI is surrounded by two round chondrules and one oval chondrule-like object. How did they get this way?
Parnallee 1096 (jb) A multitude of chondrules
Richfield 4887 (jb) Two large chondrules.
Nakhla 3887 (xpl) (jb) Basalt from Mars.
Nakhla 3887 (xpl-closeup) (jb)
Millbillillie 4547 (xpl) (jb)
Ibitira 4768 (xpl) (jb) Vesicular basalt from Vesta.
Gov. Valadares 4957 (xpl) (jb) A martian basalt.
Gov. Valadares 4957 (jb) Martian, up close.

Credit: Images labeled '(dse)' were taken by Denton S. Ebel, all others by Joseph Boesenberg, using equipment in the Dept. Earth and Planetary Sciences, Physical Sciences Division, American Museum of Natural History. Copyright adheres to AMNH.

Format: Most files (and those noted '-pc'). are saved from photoshop in 'IBM-pc byte order', except those labeled -mac. are saved with 'macintosh byte order'. All images were taken at highest resolution with a Nikon coolpix 900 3.5 Mpixel camera, and were saved from photoshop without compression.

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Last revised: 26-Jan-2008 (DSE)