Canyon Diablo Iron Meteorite Full Slice, IAB-MG, 112.54g, Etched Both Sides, Neumann Bands

Full slice from the iron that made Meteor Crater

This 112.54 g full slice of Canyon Diablo is polished and etched on both faces. Bright kamacite plates cross one another over the whole surface, and scattered through them are dozens of elongated bronze-colored inclusions lined up with the plates. In the darker grains, fine Neumann bands cross one another in sets.

Canyon Diablo is the iron meteorite recovered around Meteor Crater in northern Arizona. The Meteoritical Bulletin records it as a find, first described in 1891, and classifies it as Iron, IAB-MG.

Structure and features

Both faces show the same coarse crossing plate structure. Long kamacite plates run in several directions and meet at angles, and areas of differently oriented metal catch the light in different tones of gray as the slice is turned. Buchwald (1975) records a kamacite bandwidth of 2.0 plus or minus 0.5 mm for Canyon Diablo, which places it among the coarse octahedrites.

The inclusions are the standout feature. They appear as many small, elongated bronze bodies, most of them a few millimeters long, aligned with the kamacite plates and repeated across both faces. They have not been analyzed. Buchwald describes cohenite, an iron nickel carbide, in Canyon Diablo as rounded crystals about 3 by 0.5 mm precipitated within the kamacite plates, which matches what these inclusions look like, so cohenite is the most likely identity, but it is not confirmed for this specimen. One larger, darker elongated body sits near one edge of the second face; it has also not been analyzed.

The close-up photographs show Neumann bands as fine straight lines crossing the darker grains, with several sets intersecting in places. Thin dark lines also trace some of the grain boundaries.

This is a full slice, so the natural exterior of the meteorite runs all the way around the edge, with brown terrestrial oxide from its long exposure in the ground. The slice has been professionally stabilized by Brian McDonald of Treasure Coast Meteorite Co., and both faces carry a protective coat of Renaissance Wax.

The display stand and scale cube in the photographs are not included.

Discovery and provenance

The site was known long before the meteorites were described. According to Buchwald (1975), people lived near the crater in precolumbian times, and the remains of twelfth century pit dwellings have been reported on the outer south slope of the rim. Buchwald adds that it is quite unlikely anyone witnessed the impact itself. Pioneers and prospectors knew the area in the 1840s to 1860s, and army scouts called it Franklin's Hole in 1871; it was later known as Coon Mountain or Coon Butte.

The first thorough description came in 1891 from the geologist and mineral dealer A. E. Foote, who named the irons after Canyon Diablo, a deep canyon about 5 km west of the crater, and the railway post office of the same name. Foote could find no lava or other volcanic rock at the crater and could not explain how it formed. In the same paper, Professor Koenig reported small diamonds in the iron, a finding later confirmed by other researchers.

In 1903 a group led by the lawyer and mining engineer D. M. Barringer staked a claim to the crater and began drilling for a large iron mass they believed lay buried beneath the floor, at a time when leading geologists still doubted an impact origin. The work continued until Barringer died in 1929. Buchwald notes that whether the main mass was ever struck remained disputed. The impact origin of the crater was settled decisively in 1960, when Chao, Shoemaker and Madsen identified coesite, a high pressure form of silica, in the crushed sandstone of the crater. The crater is also known as Barringer Crater, and Buchwald recorded that it was owned by the Barringer family.

Buchwald estimated that more than 20,000 fragments, from 50 g to 639 kg, had been recovered from a roughly circular area about 15 km across centered on the crater. The Meteoritical Bulletin records a total mass of 30 t, matching the estimate of all recovered metallic specimens that Buchwald cites from Nininger (1949). Iron masses found hundreds of kilometers away, including Fair Oaks, Bloody Basin and Panamint Range, are listed in the Bulletin as synonyms and are thought to be fragments carried away from the crater area.

Sources: Buchwald (1975), Handbook of Iron Meteorites, volume 2, pages 381 and following; Chao, Shoemaker and Madsen (1960), cited below; the Meteoritical Bulletin entry.

Scientific context

The Meteoritical Bulletin classifies Canyon Diablo as Iron, IAB-MG. MG stands for main group: Canyon Diablo belongs to the main group of the IAB complex, a grouping assigned from trace element chemistry and nickel content rather than from etched structure. Buchwald reported 7.10% nickel, 0.46% cobalt, 80 ppm gallium, 320 ppm germanium and 1.9 ppm iridium, with about 1% carbon and 1% sulfur.

Many IAB irons carry inclusions of graphite, troilite and carbides, and Canyon Diablo is a well studied example. Buchwald describes troilite and graphite nodules rimmed with schreibersite and cohenite, as well as the separate cohenite crystals within the kamacite plates of the kind most likely seen in this slice.

Neumann bands are thin mechanical twins in kamacite, the low nickel iron phase, produced when a shock wave passes through the metal. After etching they show as sets of fine straight lines crossing the kamacite, and each set follows a different crystal plane. For more on the crossing plate structure, see Widmanstatten Pattern Explained.

What the research reports

The Meteoritical Bulletin lists this meteorite as Canyon Diablo, classified Iron, IAB-MG, found in 1891 in the United States with a recorded mass of 30 t. It was published in the Meteoritical Bulletin (MB 33, 1965), and its classification history runs from Iron (MB 33, 1965) to IAB (NHM Catalogue, 2000) to IAB-MG (MetBase, 2006). The Bulletin records no structural class, and the crater age given below comes from later work that replaced Buchwald's estimate. Findings come from the authors' own samples and methods and are given as the studies state them.

Buchwald (1975): the iron itself

Vagn F. Buchwald's Handbook of Iron Meteorites (University of California Press, 1975, volume 2, pages 381 and following), linked from the Bulletin entry, classifies Canyon Diablo as a coarse octahedrite (Og) with a bandwidth of 2.0 plus or minus 0.5 mm. He found Neumann bands and a range of shock structures, and showed that specimens from the crater rim had been reheated during the impact while many others were not. He describes cohenite as common, both as rims around troilite and schreibersite nodules and as rounded crystals in the Widmanstatten kamacite. Buchwald gave the best estimate of the crater's age at the time as 20,000 years, based on erosion and geological features; later dating replaced that figure.

Chao, Shoemaker and Madsen (1960): proof of impact

E. C. T. Chao, E. M. Shoemaker and B. M. Madsen published First natural occurrence of coesite (Science, volume 132, pages 220 to 222, 1960). Coesite had previously been known only from the laboratory. Finding it in sheared Coconino sandstone at Meteor Crater showed that the rock had been subjected to pressures far beyond anything a volcanic explosion produces, and gave geologists a mineral marker for recognizing impact craters elsewhere.

Phillips et al. (1991) and Nishiizumi et al. (1991): the age of the crater

Two studies published together in Geochimica et Cosmochimica Acta, volume 55 (1991), dated the crater using isotopes produced by cosmic rays in rock exposed by the impact. F. M. Phillips and colleagues, in Age and geomorphic history of Meteor Crater, Arizona, from cosmogenic 36Cl and 14C in rock varnish (pages 2695 to 2698), measured chlorine-36 in boulders thrown out of the crater and reported a mean age of 49,700 plus or minus 850 years, consistent with earlier thermoluminescence dating. K. Nishiizumi and colleagues, in In situ 10Be-26Al exposure ages at Meteor Crater, Arizona (pages 2699 to 2703), reported a lower limit of 49,200 plus or minus 1,700 years. Together they place the impact roughly 50,000 years ago.

Why this listing calls Canyon Diablo a coarse octahedrite

The Meteoritical Bulletin Database records iron meteorites by chemical group only, so its entry for Canyon Diablo reads Iron, IAB-MG, with no structural class. The structural class used here comes from Buchwald (1975), cited above, which the Bulletin entry links directly.

Frequently asked questions

Is this meteorite authenticated?
Canyon Diablo is classified in the Meteoritical Bulletin Database as Iron, IAB-MG, and the entry is linked at the end of this listing. Treasure Coast Meteorite Co. is IMCA member #3323. This specimen includes a certificate of authenticity documenting its weight, classification, and provenance.

Is Canyon Diablo a fall or a find?
A find. The Meteoritical Bulletin records it as found in 1891, with no observed fall. Dating of the crater places the impact roughly 50,000 years ago.

What are the bronze inclusions?
They have not been analyzed. Their shape, color and alignment with the kamacite plates match Buchwald's (1975) description of cohenite, an iron nickel carbide that is common in Canyon Diablo, so cohenite is the most likely identity, but it is not confirmed for this specimen.

What does full slice mean?
The slice was cut all the way across the original mass, so the natural exterior edge of the meteorite runs around the entire outline. Both faces have been polished and etched.

What are Neumann bands?
Neumann bands are shock deformation features in kamacite. When a shock wave passes through the metal, the crystal lattice twins along specific planes, and after etching these twins show as fine parallel lines within individual kamacite crystals.

Has this iron been stabilized?
Yes. This slice was professionally stabilized by Brian McDonald of Treasure Coast Meteorite Co. before listing, as every iron meteorite we sell now is, to help guard against the rust that can develop in iron meteorites over time. Both faces were then coated with Renaissance Wax.

What is included with this specimen?
The 112.54 g slice as photographed and a certificate of authenticity. Display stands and scale cubes shown in the photographs are not included.

How should I store an etched iron meteorite?
Keep it in a low humidity environment. Etched surfaces react to moisture more readily than natural surfaces, so a silica gel pack in the storage container helps prevent oxidation. Because this specimen has been professionally stabilized and coated with Renaissance Wax, no oil is needed. Handle it with gloves or clean, dry hands.

Collector significance

Canyon Diablo is the meteorite behind Meteor Crater, the crater that helped prove impacts shape planetary surfaces. Most Canyon Diablo on the market is sold as small uncut individuals. This full slice is etched on both faces, keeps the natural edge all the way around, and shows a dense field of bronze inclusions and Neumann bands that are visible without magnification.

For more iron meteorites, see our full Iron Meteorites collection.

Meteoritical Bulletin entry: Canyon Diablo | Classification: Iron, IAB-MG | Find, United States, 1891 | Treasure Coast Meteorite Co., IMCA #3323