Triangular gray meteor sample known as Canyon Diablo meteorite. These meteorites are named after a nearby canyon of the same name, and consist of fragments of the asteroid that created Barringer Crater (Meteor Crater) near Flagstaff, Arizona, which fell approximately 50,000 years ago. This iron octahedrite meteorite demonstrates the Widmanstatten pattern, a crystalline structure formed by interwoven bands of the nickel-iron minerals, kamacite, and taenite. Kamacite is found on Earth only in meteorites. Widmanstatten patterns are created as the meteorite cools; at high temperatures both iron and nickel have face-centered lattices. When the meteorite is formed it starts out as entirely molten taenite (greater than 1500 degrees C) and as it cools past 723 degrees C, the primary metastable phase of the alloy changes into taenite and kamacite begins to precipitate out.
- Catalog Number:
- 45334
- Object/Specimen Description:
- Specimen Count:
- 1
- Precise Locality:
Canyon Diablo
- Locality:
- US Southwest (NM, AZ, UT, NV)
- Collecting Locality:
- North America, United States, Arizona, Coconino County
- Cabinet:
- 26
- Drawer/Shelf:
- 04
A meteorite is any fragment of rock from the solar system that passes through the atmosphere and survives its impact with Earth. About 3 percent of meteorites found on Earth's surface are made almost entirely of the metals iron and nickel, and are called iron meteorites. When the parent body was partially molten, the heavy iron and nickel metals segregated from the less dense silicate minerals and concentrated in the core, just as metals sank to Earth's core while our planet was forming. Scientists believe that these dense metallic fragments may have come from the cores of certain minor planets, called M-type asteroids, when they were blasted apart by a collision with other bodies during the early days of the solar system, more than 4 billion years ago.
The mineral composition of meteorites ranges from nearly solid iron and other metals to nearly solid silicates. In general, iron meteorites are much denser than stony meteorites. If two meteorites of the same size enter Earth's atmosphere, the stony meteorite is more likely to break into pieces and burn up completely than the iron meteorite. In fact, some carbonaceous chondrites, which contain organic compounds and water in addition to silicates, can crumble in a human's hand. Other stony meteorites are hard to the touch and may resemble terrestrial rocks. They contain silicate mineral grains, with some metal grains mixed in. These stones came from smaller rocks and dust that accreted (stuck to each other) during the earliest days of the solar system, 4.5 billion years ago.