User:Marshallsumter/Radiation astronomy1/Meteoritic irons

Iron meteorites, aka siderites, or ferrous meteorites are meteorites that consist overwhelmingly of iron–nickel alloys that usually consists of two mineral phases: kamacite and taenite. Most iron meteorites originate from planetary cores of planetesimals.

Meteoric iron, a characteristic iron–nickel alloy, was used by various ancient peoples thousands of years before the Iron Age. Such iron, being in its native metallic state, required no smelting of ores.

While they are fairly rare compared to the stony meteorites, comprising about 5.7% of witnessed falls, they have historically been heavily over-represented in meteorite collections.

Iron meteorites account for almost 90% of the mass of all known meteorites, about 500 tons.

On the right is apparently another iron meteorite discovered in a desert that left no crater.

All or nearly all iron meteorites are magnetic. Passage through the Earth's magnetic field and the natural electric field of the Earth may cause these iron meteorites to slow down sufficiently so as to land without a crater.

"A great demolition derby, with a chaotic mess of asteroids and forming planets constantly slamming into each other, took place in the early solar system between 7.8 million and 11.7 million years after the sun formed [...]."

"Our additional measurements of platinum isotope abundances allowed us to correct the silver isotope measurements for distortions caused by cosmic irradiation of the samples in space. So we were able to date the timing of the collisions more precisely than ever before."

"The dates [...] were between 7.8 million and 11.7 million years after the formation of the solar system".

"Everything seems to have been smashing together at that time."

This "chaos [...] was largely related to the dissipation of the solar nebula, the cloud of gas that formed the sun."

"The gas giant planets — in particular, Jupiter and Saturn — migrated around the early solar system, and their gravitational influence disrupted the orbits of smaller bodies, ushering them to form the asteroid belt and the Kuiper Belt."

"One model in particular, known as the "Grand Tack," purports that Jupiter migrated in-system, as close to the sun as Mars is today, before Saturn's gravity influenced Jupiter to migrate outward again to its present position. The Grand Tack model predicts that this event would have taken place about 10 million years into the history of the solar system."

Structural meteorites
At temperatures below 1100 K, man-made zirconium alloys belong to the hexagonal crystal family (HCP), with its microstructure, revealed by chemical attack, showing needle-like grains typical of a Widmanstätten pattern as in the image on the right, which upon annealing below the phase transition temperature (α-Zr to β-Zr) become equiaxed with sizes varying from 3 to 5 μm.

The structural classification of meteorites is based on the presence or absence of the Widmanstätten pattern, which can be assessed from the appearance of polished cross-sections that have been etched with acid. This is connected with the relative abundance of nickel to iron.


 * Ataxites (D): very high nickel, no Widmanstätten pattern, rare.


 * Hexahedrites (H): low nickel, no Widmanstätten pattern, may present Neumann lines.


 * Octahedrites (O): average to high nickel, Widmanstätten patterns, most common class, divided up on the basis of the width of the kamacite lamellae from coarsest to finest.


 * Fine (Of): lamellae width 0.2–0.5 mm.


 * Finest (Off): lamellae width < 0.2 mm.


 * Coarse (Og): lamellae width 1.3–3.3 mm.


 * Coarsest (Ogg): lamellae width > 3.3 mm.


 * Medium (Om): lamellae width 0.5–1.3 mm.


 * Plessitic (Opl): a transitional structure between octahedrites and ataxites

Ataxites (D)
Ataxites (D): very high nickel, no Widmanstätten pattern, rare.

Santiago Papasquiero meteorites


The Santiago Papasquiero meteorites consist of a finely crystalline mix of kamacite & taenite, plus other minor minerals. Santiago Papasquiero is a strange ataxite that appears to be a completely metamorphosed and recrystallized octahedrite. Most recrystallized octahedrites still retain vague hints of the original Widmanstätten structure. This meteorite doesn't have any, so it isn’t an octahedrite - it’s an ataxite.

Published chemical info. indicates that Santiago Papasquiero has 7.5% nickel content overall. The kamacite component has 6.8% Ni. The taenite component has 30% Ni.

Hexahedrites (H)
Hexahedrites (H): low nickel, no Widmanstätten pattern, may present Neumann lines.

Hexahedrites are a structural class of iron meteorite, composed almost exclusively of the nickel–iron alloy kamacite and are lower in nickel content than the octahedrites. The nickel concentration in hexahedrites is always below 5.8% and only rarely below 5.3%.

Neumann lines: parallel lines that cross each other at various angles, and are indicative of impact shock on the parent body.

Concentrations of trace elements (germanium, gallium and iridium) are used to separate the iron meteorites into chemical classes, which correspond to separate asteroid parent bodies, where chemical classes that include hexahedrites are:

Coahuila meteorites
Only fragments found in Coahuila, that are hexahedrites and fall into the IIAB meteorite group should be called Coahuila meteorites.

The mineral Daubréelite was first described in this meteorite.


 * 1) Group: IIAB meteorites.
 * 2) Structural classification: Hexahedrite.
 * 3) Country: Mexico.
 * 4) Region: Coahuila.
 * 5) Coordinates: 28°42'N 102°44'W.
 * 6) Observed fall: No.
 * 7) Found date: 1837.
 * 8) TKW: 2100 kg.

Octahedrites
Octahedrites derive their name from the crystal structure paralleling an octahedron.

In gaps between the kamacite and taenite lamellae, a fine-grained mixture called plessite is often found, with an iron nickel phosphide, schreibersite, in most nickel-iron meteorites, an iron-nickel-cobalt carbide, cohenite, graphite and troilite in rounded nodules up to several cm in size.

Cutting the meteorite along different planes affects the shape and direction of Widmanstätten figures because kamacite lamellae in octahedrites are precisely arranged. Opposite faces are parallel so, although an octahedron has 8 faces, there are only 4 sets of kamacite plates. Iron and nickel-iron form crystals with an external octahedral structure only very rarely, but these orientations are still plainly detectable crystallographically without the external habit. Cutting an octahedrite meteorite along different planes (or any other material with octahedral symmetry, which is a sub-class of cubic symmetry) will result in one of these cases:
 * perpendicular cut to one of the three (cubic) axes: two sets of bands at right angles each other
 * parallel cut to one of the octahedron faces (cutting all 3 cubic axes at the same distance from the crystallographic center) : three sets of bands running at 60° angles each other
 * any other angle: four sets of bands with different angles of intersection.

Octahedrites can be grouped by the dimensions of kamacite lamellae in the Widmanstätten pattern, which are related to the nickel content:
 * Coarsest octahedrites, lamellae width >3.3 mm, 5-9% Ni, symbol Ogg
 * Coarse octahedrites, lamellae 1.3-3.3 mm, 6.5-8.5% Ni, symbol Og
 * Medium octahedrites, lamellae 0.5-1.3 mm, 7-13% Ni, symbol Om
 * Fine octahedrites, lamellae 0.2-0.5 mm, 7.5-13% Ni, symbol Of
 * Finest octahedrites, lamellae <0.2 mm, 17-18% Ni, symbol Off
 * Plessitic octahedrites, kamacite spindles, a transitional structure between octahedrites and ataxites, 9-18% Ni, symbol Opl

Zacatecas meteorites
Brecciated octahedrite.

Fine octahedrites (Of)
Fine octahedrites, 7.4–9.4% Ni, 1.6–2.4 ppm Ga, 0.09–0.14 ppm Ge, 0.4-4 ppm Ir, Ge-Ni correlation positive.

Muonionalusta meteorites
The first fragment of the Muonionalusta meteorite was found in 1906 near the village of Kitkiöjärvi. Around forty pieces are known today, some being quite large, other fragments have been found in a 25 x area in the Pajala district of Norrbotten County, approximately 140 km north of the Arctic Circle.

The meteorite was first described in 1910 by Professor A. G. Högbom, who named it after the nearby place Muonionalusta on the Muonio River. The Muonionalusta meteorite, probably the oldest known meteorite (4.5653 ± 0.0001 billion years), marks the first occurrence of stishovite in an iron meteorite.

It is the oldest discovered meteorite impacting the Earth during the Quaternary Period, about one million years ago and is quite clearly part of the iron core or mantle of a planetoid, which shattered into many pieces upon its fall on our planet. Since landing on Earth the meteorite has experienced four ice ages, was unearthed from a glacial moraine in the northern tundra], and has a strongly weathered surface covered with cemented faceted pebbles.

New analysis of this strongly shock-metamorphosed iron meteorite has shown a content of 8.4% nickel and trace amounts of rare elements—0.33 ppm gallium, 0.133 ppm germanium and 1.6 ppm iridium and contains the minerals chromite, daubréelite, schreibersite, akaganéite and inclusions of troilite.

For the first time, analysis has proved the presence of a form of quartz altered by extremely high pressure—stishovite, probably a pseudomorphosis after tridymite. From the article "First discovery of stishovite in an iron meteorite": Stishovite, a high pressure polymorph of SiO2, is an exceptionally rare mineral...and has only been found in association with a few meteorite impact structures.... Clearly, the meteoritic stishovite cannot have formed by isostatic pressure prevailing in the core of the parent asteroid.... One can safely assume then that stishovite formation (in the Muonionalusta meteorite) is connected with an impact event. The glass component might have formed directly as a shock melt....

The lead isotope dating in the Muonionalusta meteorite concluded the stishovite was from an impact event hundreds of millions of years ago: "The presence of stishovite signifies that this meteorite was heavily shocked, possibly during the 0.4 Ga [billion years] old breakup event indicated by cosmic ray exposure...."

Fragments of the Muonionalusta meteorite are held by numerous institutions around the world.


 * Geological Institute, Uppsala, 15 kg.
 * Naturhistorisches Museum, Vienna, 96 g.
 * Museum für Naturkunde, Berlin, 82 g.
 * Max Planck Society (Max Planck Institute), Mainz, 96.3 g.
 * Paneth Collection (also at the Max Planck Institute), Mainz, 142.5 g.
 * National Museum of Natural History, Washington, 197 g.
 * American Museum of Natural History, New York, 84 g.
 * Field Museum of Natural History, Chicago, 65.2 g.
 * University of California, Los Angeles, 55 g.
 * Vernadsky State Geological Museum, Moscow 2404 g.
 * Observatory and Planetarium Brno, Czech Republic, 21 kg.
 * Rahmi M. Koç Museum, Istanbul.


 * 1) Type: IVA (Of).
 * 2) Class: Octahedrite.
 * 3) Group: Iron.
 * 4) Structural classification: Fine Octahedrite.
 * 5) Composition: Ni, Ga, Ge.
 * 6) Country: Sweden.
 * 7) Region: Norrbotten.
 * 8) Coordinates: 67°48'N 23°6.8'E.
 * 9) Observed fall: No.
 * 10) Found date: 1906.
 * 11) Strewn field: Yes.

Finest octahedrites (Off)

 * Finest octahedrites, lamellae <0.2 mm, 17-18% Ni, symbol Off.

NWA 2680
NWA 2680 is a silicate-rich iron meteorite class IAB-sLH, finest octahedrite (Off) from the Saharan desert. The final analysis shows that this is a rare member of the IAB-related meteorites. It is distinguished by its high Cu and relatively high Ni concentrations. This meteorite has melted troilite filled with clasts of olivine and primitive achondrites. It has a finest octahedrite etch pattern with a nickel content of 13.7%.

Coarse octahedrites (Og)

 * Coarse octahedrites, lamellae 1.3-3.3 mm, 6.5-8.5% Ni, symbol Og.

Toluca meteorites
The meteorites probably crashed towards the Earth more than 10,000 years earlier.

These iron meteorites are a coarse octahedrite, chemical type IAB meteorites-sLL.

The mean composition is 90.5% Fe and 8.1% Ni.

They often contain large troilite inclusions.
 * 1) Group: IAB meteorites-sLL.
 * 2) Structural classification: Coarse Octahedrite.
 * 3) Composition: 90.5% Fe; 8.1% Ni.
 * 4) Country: Mexico.
 * 5) Region: Toluca Valley, Jiquipilco, Mexico State.
 * 6) Coordinates: 19.45°N, -99.58333°W.
 * 7) Fall date: >10,000 years ago.
 * 8) Found date: about 1776.
 * 9) TKW: 3 tonnes.

Coarsest octahedrites Ogg

 * Coarsest octahedrites, lamellae width >3.3 mm, 5-9% Ni, symbol Ogg.

Morasko meteorites
"The Morasko meteorite belongs to the coarse octahedrite group and contains 92% Fe, 6.7% Ni, and less than 1% Co, P, S, Cu, and C."

"The Morasko meteorite belongs to the coarse octahedrite (Ogg) group (J. Polkrzywnicki, 1964; B, Dominik, 1976)."

"The Morasko meteorite contains the following minerals: kamacite, the 𝛂-phase of iron-nickel about 90 %, tenite, the 𝛄-phase of iron-nickel 0.5 %, troilite several per cent, graphite about 1 %, cloftonite, schreibersite about 1.5 %, rhabdite about 1 %, cohenite, sphalerite about 0.2 %, whitlockite, as well as secondary minerals magnetite and goethite (B. Dominik, 1976)."

Medium octahedrites (Om)

 * Medium octahedrites, lamellae 0.5-1.3 mm, 7-13% Ni, symbol Om.

Treysa meteorites
Iron meteorite is composed of iron-nickel (Medium octahedrite, group III B-ANOM) with Widmanstätten pattern, Weight after finding 63.3 kg, depth of impression: 1.6 m, crater ca. 1.5 x 1 m.

Plessitic octahedrites (Opl)

 * Plessitic octahedrites, kamacite spindles, a transitional structure between octahedrites and ataxites, 9-18% Ni, symbol Opl.

NWA 859
Sample's weight is 29.4 gram, measurements 31.8 х 21.2 х 15.9 mm. Taza was found in Northwest Africa in during 2001.

Asteroid parental bodies
A newer chemical classification scheme based on the proportions of the trace elements Ga, Ge and Ir separates the iron meteorites into classes corresponding to distinct asteroid parent bodies. This classification is based on diagrams that plot nickel content against different trace elements (e.g. Ga, Ge and Ir). The different iron meteorite groups appear as data point clusters.

There were originally four of these groups designated by the Roman numerals I, II, III, IV. When more chemical data became available these were split, e.g. Group IV was split into IVA meteorites (IVA) and IVB meteorites. Even later some groups got joined again when intermediate meteorites were discovered, e.g. IIIA and IIIB were combined into the IIIAB meteorites.

In 2006 iron meteorites were classified into 13 groups (one for uncategorized irons):


 * IAB meteorite (IAB).


 * IA: Medium and coarse octahedrites, 6.4-8.7% Ni, 55-100 ppm Ga, 190-520 ppm Ge, 0.6–5.5 ppm Ir, Ge-Ni correlation negative.


 * IB: Ataxites and medium octahedrites, 8.7–25% Ni, 11–55 ppm Ga, 25–190 ppm Ge, 0.3-2 ppm Ir, Ge-Ni correlation negative.


 * IC meteorites (IC): 6.1–6.8% Ni. The Ni concentrations are positively correlated with As (4–9 μg/g), Au (0.6–1.0 μg/g) and P (0.17–0.40%) and negatively correlated with Ga (54–42 μg/g), Ir (9–0.07 μg/g) and W (2.4–0.8 μg/g).


 * IIAB meteorites (IIAB).


 * IIA: Hexahedrites, 5.3–5.7% Ni, 57–62 ppm Ga, 170–185 ppm Ge, 2-60ppm Ir.


 * IIB: Coarsest octahedrites, 5.7–6.4% Ni, 446-59 pm Ga, 107–183 ppm Ge, 0.01–0.5 ppm Ir, Ge-Ni correlation negative.


 * IIC meteorite (IIC0: Plessitic octahedrites, 9.3–11.5% Ni, 37–39 ppm Ga, 88–114 ppm Ge, 4–11 ppm Ir, Ge-Ni correlation positive.


 * IID meteorite (IID): Fine to medium octahedrites, 9.8–11.3%Ni, 70–83 ppm Ga, 82–98 ppm Ge, 3.5–18 ppm Ir, Ge-Ni correlation positive.


 * IIE iron meteorite (IIE): octahedrites of various coarseness, 7.5–9.7% Ni, 21–28 ppm Ga, 60–75 ppm Ge, 1–8 ppm Ir, Ge-Ni correlation absent.


 * IIF.


 * IIG meteorites (IIG): Hexahedrites with coarse schreibersite. Meteoric iron has low nickel concentration.


 * IIIAB meteorites (IIIAB): Medium octahedrites, 7.1–10.5% Ni, 16–23 ppm Ga, 27–47 ppm Ge, 0.01-19 ppm Ir.


 * IIICD meteorite (IIICD): Ataxites to fine octahedrites, 10–23% Ni, 1.5–27 ppm Ga, 1.4–70 ppm Ge, 0.02–0.55 ppm Ir.


 * IIIE meteorites (IIIE): Coarse octahedrites, 8.2–9.0% Ni, 17–19 ppm Ga, 3–37 ppm Ge, 0.05-6 ppm Ir, Ge-Ni correlation absent.


 * IIIF meteorites (IIIF): Medium to coarse octahedrites, 6.8–7.8% Ni,6.3–7.2 ppm Ga, 0.7–1.1 ppm Ge, 1.3–7.9 ppm Ir, Ge-Ni correlation absent.


 * IVA meteorites (IVA): Fine octahedrites, 7.4–9.4% Ni, 1.6–2.4 ppm Ga, 0.09–0.14 ppm Ge, 0.4-4 ppm Ir, Ge-Ni correlation positive.


 * IVB meteorite (IVB): Ataxites, 16–26% Ni, 0.17–0.27 ppm Ga, 0,03–0,07 ppm Ge, 13–38 ppm Ir, Ge-Ni correlation positive.


 * Ungrouped meteorites. This is actually quite a large collection (about 15% of the total) of over 100 meteorites that do not fit into any of the larger classes above, and come from about 50 distinct parent bodies.

The iron meteorites were previously divided into two classes: magmatic irons and non magmatic or primitive irons. Now this definition is deprecated.

IAB meteorites
IAB meteorites are a group of iron meteorites according to their overall composition and a group of primitive achondrites because of silicate inclusions that show a strong affinity to winonaites and chondrites.

Structurally they can be hexahedrites, fine to coarse octahedrites, or even ataxites. Most of them are octahedrite with medium to coarse taenite-lamella and distinct Widmanstätten patterning.

The silicate inclusions are composed of low-Ca pyroxene, high-Ca pyroxene, olivine, plagioclase, troilite, graphite, different phosphates, meteoric iron and traces of daubréelite and chromite. There are also similarities with the IIICD meteorites, but it is not yet clear whether they are also part of that parent body.

The IAB group was created from the older IA and IB groups. Some authors also prefer to call it IAB complex.

There are numerous subdivisions of the IAB group:


 * IAB main group
 * sLL subgroup
 * sLM subgroup (originally IIIC)
 * sLH subgroup (originally IIID)
 * sHL subgroup
 * sHH subgroup (includes Gay Gulch trio)
 * Udei Station grouplet
 * Pitts grouplet
 * Algarrabo duo
 * Mundrabilla duo
 * Britstown duo
 * NWA 468 duo
 * Twin City duo
 * solo irons related to IAB
 * IAB related?

The winonaites and the IAB meteorites may share the same parent body.

Canyon Diablo meteorites
Meteor Crater (Barringer Crater) in the Arizona desert was formed by the impact of an octahedrite ~49,000 years ago during the Late Pleistocene. The rock shown here is a fragment of the impactor, the Canyon Diablo Meteorite. Such fragments have been collected for decades from the desert surrounding the crater. Canyon Diablo is composed of ~90% kamacite, ~1-4% taenite, and up to 8.5% troilite-graphite nodules (FeS & C). The original mass has been estimated to be 100 feet across & about 60,000 tons. Canyon Diablo rocks are well dated to 4.55 billion years.


 * 1) Group: IAB-MG.

Mundrabilla meteorites
"The Mundrabilla iron meteorite and meteorite irons found around the Nullarbor Plain in Western Australia may have all been found above or just below the surface."

The main mass of the Mundrabilla meteorite weighs 12.4 tonnes and is shown first on the right.

"There are a number of large Mundrabilla iron meteorites but there are also the much smaller and strangely shaped Mundrabilla meteorite irons."

"In April 1966, two large masses estimated to be 10-12 tons and 4-6 tons [second on the left], later named Mundrabilla, were found approximately 200 yards (ca. 183 m) apart and described by the finders R. B. Wilson and A. M. Cooney."

"The 12.4 tonne main mass (recently accurately weighed) of the Mundrabilla meteorite shower is the largest meteorite yet found in Australia. In all, some 22 tonnes of fragments of this ancient meteorite shower have been recovered."

"Mundrabilla meteorite irons are strange little pieces of iron, twisted into odd shapes."

Second on the right is perhaps the third largest piece of the Mundrabilla meteorite.

The second image on the left is another piece of the Mundrabilla meteorite still covered in some of the sediment and partial weathering produced after its fall.

One small fragment of the Mundrabilla iron meteorite looks like it is thumb-printed. It is the third image down on the right.

The last fragment here of the Mundrabilla iron meteorite on the left third down is about 9 cm on edge and has a hole in it.


 * 1) Group: IAB.

IA meteorites

 * IA: Medium and coarse octahedrites, 6.4-8.7% Ni, 55-100 ppm Ga, 190-520 ppm Ge, 0.6–5.5 ppm Ir, Ge-Ni correlation negative.

Odessa meteorites
Over 1500 meteorites have been recovered from the surrounding area over the years, the largest of which weighed approximately 300 lb.

The crater is 550 ft in diameter and the age is estimated to be around 63,500 years (Pleistocene or younger).

IB meteorites

 * IB: Ataxites and medium octahedrites, 8.7–25% Ni, 11–55 ppm Ga, 25–190 ppm Ge, 0.3-2 ppm Ir, Ge-Ni correlation negative.

IC meteorites

 * IC meteorites (IC): 6.1–6.8% Ni. The Ni concentrations are positively correlated with As (4–9 μg/g), Au (0.6–1.0 μg/g) and P (0.17–0.40%) and negatively correlated with Ga (54–42 μg/g), Ir (9–0.07 μg/g) and W (2.4–0.8 μg/g).

Sikhote-Alin meteorites
Large iron meteorite falls have been witnessed and fragments recovered but never before, in recorded history, a fall of this magnitude. An estimated 23 tonnes of fragments survived the fiery passage through the atmosphere and reached the Earth.

As the meteor, traveling at a speed of about 14 km/s, entered the atmosphere, it began to break apart, and the fragments fell together, some burying themselves 20 ft deep. At an altitude of about 5.6 km, the largest mass apparently broke up in a violent explosion called an air burst.

This orbit was ellipse-shaped, with its point of greatest distance from the sun situated within the asteroid belt, similar to many other small bodies crossing the orbit of the Earth. Such an orbit was probably created by collisions within the asteroid belt.

Sikhote-Alin is a massive fall with the pre-atmospheric mass of the meteoroid estimated at approximately 90000 kg. A more recent estimate by Tsvetkov (and others) puts the mass at around 100000 kg.

Estimated the post-atmospheric mass of the meteoroid at some 23000 kg.

The Sikhote-Alin meteorite is classified as an iron meteorite belonging to the meteorite group IIAB and with a coarse octahedrite structure. It is composed of approximately 93% iron, 5.9% nickel, 0.42% cobalt, 0.46% phosphorus, and 0.28% sulfur, with trace amounts of germanium and iridium. Minerals present include taenite, plessite, troilite, chromite, kamacite, and schreibersite.
 * 1) Group: IIAB
 * 2) Structural classification: Octahedrite, coarsest
 * 3) Composition= 93% Fe, 5.9% Ni, 0.42% Co, 0.46% P, 0.28% S
 * 4) Country= Russia
 * 5) Region= Sikhote-Alin Mountains, Primorsky Krai]], Far Eastern Federal District
 * 6) Coordinates: 46.16°N, 134.65333°W
 * 7) Observed fall: Yes
 * 8) Fall date: February 12, 1947
 * 9) Weight: >23 t
 * 10) Strewn field: Yes

"Group lIB. 5.90% Ni, 0.42% Co, 0.46% P, 0.28% S, 52 ppm Ga, 161 ppm Ge, 0.03 ppm Ir."

IIA meteorites

 * IIA: Hexahedrites, 5.3–5.7% Ni, 57–62 ppm Ga, 170–185 ppm Ge, 2-60ppm Ir.

IIB meteorites

 * IIB: Coarsest octahedrites, 5.7–6.4% Ni, 446-59 pm Ga, 107–183 ppm Ge, 0.01–0.5 ppm Ir, Ge-Ni correlation negative.

Ainsworth meteorites
Ainsworth meteorite is texturally classified as a coarsest octahedrite (aka granular hexahedrite; aka kamacite octahedrite), meaning it has the largest size of metal crystals known in iron meteorites, and lacks thin, criss-crossing blades, (Me 1059, FMNH public display, Field Museum of Natural History, Chicago, Illinois, USA).

IIC meteorites

 * IIC meteorite (IIC0: Plessitic octahedrites, 9.3–11.5% Ni, 37–39 ppm Ga, 88–114 ppm Ge, 4–11 ppm Ir, Ge-Ni correlation positive.

IID meteorites

 * IID meteorite (IID): Fine to medium octahedrites, 9.8–11.3%Ni, 70–83 ppm Ga, 82–98 ppm Ge, 3.5–18 ppm Ir, Ge-Ni correlation positive.

IIE meteorites

 * IIE iron meteorite (IIE): octahedrites of various coarseness, 7.5–9.7% Ni, 21–28 ppm Ga, 60–75 ppm Ge, 1–8 ppm Ir, Ge-Ni correlation absent.

IIG meteorites
While cooling the parent body reached the IIAB field, then followed the field to the eutectic point where the remaining melt cavities formed the IIG meteorites.

Trace elements of IIAB meteorites and IIG meteorites are offset, which was interpreted as (1) the two groups forming on a separate planetesimal or (2) melt immiscibility, while the planetesimal was cooling off: first meteoric iron crystallized into a network of cavities and channels, but eventually crystallization cut off the channels and made cavities of trapped melt, when the remaining melt reached the eutectic point, the cavities crystallized a mixture of schreibersite and meteoric iron.

The matrix of this process would form the IIAB meteorites, while the cavities would form the IIG meteorites.


 * IIG meteorites (IIG): Hexahedrites with coarse schreibersite. Meteoric iron has low nickel concentration.

The Bellsbank meteorite, La Primitiva meteorite and Tombigbee meteorite meteorites were iron meteorites that were found to have chemical and structural similarities.

It was proposed that the three meteorites should be grouped into the "Bellsbank Trio" grouplet.

The grouplet status that requires five specimen was filled by the Twannberg meteorite and by the Guanaco meteorite.

The sixth member is the Auburn meteorite.

IIGs contain large amounts of phosphorus in the form of schreibersite and very low concentrations of sulfur.


 * 1) Class: Magmatic.
 * 2) Structural classification: Hexahedrite.
 * 3) Parent body: IIG-IIAB.
 * 4) Composition: Meteoric iron (kamacite), nickel (4.1 to 4.9 %), much schreibersite (phosphorus), little sulfur.
 * 5) Number of specimens: 6.

Bellsbank meteorites
Only one specimen with a mass of 38 kg was dug out from a field near Bellsbank, northwest of Kimberley, South Africa.

The meteorite was first described in 1959.

Upon etching the meteorite shows Neumann lines. The meteoric iron has nickel concentrations as low as 1.6%.

After 5 meteorites were found the grouplet called "Bellsbank Trio" was renamed IIG meteorites (IIG group).


 * 1) Type: Iron meteorite.
 * 2) Group: IIG.
 * 3) Structural classification: Hexahedrite.
 * 4) Parent body: IIG-IIAB.
 * 5) Composition: Meteoric iron (Kamacite), Schreibersite
 * 6) Country: Bellsbank, South Africa.
 * 7) Coordinates: 28°5'S 24°5'E.
 * 8) Observed fall: No
 * 9) Found date: 1955
 * 10) TKW: 38 kg

Twannberg meteorites
The Twannberg meteorite is the only meteorite of the IIG group found in Europe and the largest meteorite ever found in Switzerland.

The first fragment (15.91 kg) was found on 9 May 1984 in a barley field near Twann, after it had been ploughed (Twannberg I), and two additional fragments were found in an unnatural setting: one fragment (II) win an attic in Twann and another (III) in the Natural History Museum of Bern (Naturhistorisches Museum Bern), in a collection received from the Museum Schwab in Biel where it had been labeled as hematite. Twannberg IV, V and VI were found in the creek Twannbach.

The meteorite is named after Twannberg (from German: Twann mountain), a mountain that lies north of Twann.

The find location is a glacial till deposit, paired with minerals found in the oxidized surface of the meteorite are an indicator that the meteorite fell on the Rhone glacier and was transported to Twann during the Würm ice age and then deposited there.

The preatmospheric mass was estimated to be at least 11,000 kg, where the surface of the meteorite is covered in an oxidation layer.


 * 1) Type: Iron meteorite.
 * 2) Group: IIG meteorites.
 * 3) Structural classification: Hexahedrite.
 * 4) Parent body: IIG-IIAB.
 * 5) Composition: Meteoric iron 5.1 % Ni (Kamacite), Schreibersite.
 * 6) Country: Switzerland.
 * 7) Region: Canton of Bern.
 * 8) Coordinates: 47°7'28"N 7°10'44"E.
 * 9) Observed fall: No.
 * 10) Found date: 9 May 1984.
 * 11) TKW: 20.69 kg (6 fragments).

IIIAB meteorites

 * IIIAB meteorites (IIIAB): Medium octahedrites, 7.1–10.5% Ni, 16–23 ppm Ga, 27–47 ppm Ge, 0.01-19 ppm Ir.

Cape York meteorites
"Cape York iron meteorites are separate lumps of iron but have been grouped together as fragments of the same iron meteorite, as they are found around the same location. The iron pieces known as the Women and the Dog were found about 25 meters from each other on the mainland and Ahnighito was found on an island. They were found above the ground and with no visible crater around them, even for the largest one called Ahnighito."

Cape York is in Savissivik, Northwest Greenland. Ahnighito (the Tent) weighs 31 metric tons; the Woman, weighs 3 metric tons; the Dog, weighs 400 kilograms, Savik I 3.4 tons, Savik II 7.8 kg, and Agpalilik about 15 tons.

"The meteorite lay on an ice-free slope 500 m from the shore and was partly covered with gneiss boulders. There was no crater and no crushing of rocks discovered."

The Cape York meteorite, also known as the Innaanganeq meteorite, is one of the largest known iron meteorites, classified as a medium octahedrite in chemical group IIIAB meteorites. In addition to many small fragments, at least eight large fragments with a total mass of 58 tons have been recovered, the largest weighing 31 tonne. The meteorite is loosely named after the location where the largest fragment was found: 23 mi east of Cape York, in Savissivik, Meteorite Island, Greenland.

The largest fragment was recovered in an area where the landscape consists of "flowing" gravel or clay-like sediments on permafrost, indicating that it had been in place for no more than a few thousand years. Other estimates have put the date of the fall as 10,000 years ago.


 * 1) Group: IIIAB
 * 2) Structural classification: Octahedrite, medium
 * 3) Composition= 7.58% Ni, 19.2 ppm Ga, 36.0 ppm Ge, 5.0 ppm Ir
 * 4) Country: Greenland
 * 5) Region= Avannaata
 * 6) Coordinates: 76.13333°N, -64.93333°W
 * 7) Fall date: A few thousand years ago
 * 8) Found_date: Prehistoric
 * 9) TKW: 58,200 kg

Each of the most important fragments of Cape York has its own name (listed in order of discovery date by foreigners):


 * 1) Ahnighito (the Tent), 30900 kg, 1884–1897, Meteorite Island, 76°04'N – 64°58'W
 * 2) Woman, 3000 kg, 1897, Saveruluk, 76°09'N – 64°56'W
 * 3) Dog, 400 kg, 1897, Saveruluk, 76°09'N – 64°56'W
 * 4) Savik I, 3,400 kg, 1913, Savequarfik, 76°08'N – 64°36'W
 * 5) Thule, 48.6 kg, summer 1955, Thule, 76°32'N – 67°33'W
 * 6) Savik II, 7.8 kg, 1961, Savequarfik, 76°08'N – 64°36'W
 * 7) Agpalilik (the Man), 20000 kg, 1963, Agpalilik, 76°09'N – 65°10'W
 * 8) Tunorput, 250 kg, 1984

Laguna Manantiales meteorites
The Laguna Manantiales meteorite is an iron octahedrite, class IIIAB, 92 kg, found at 48°35' S, 67°25' W, in 1945, at Laguna Manantiales, Santa Cruz, Argentina.

Willamette Meteorites
The Willamette meteorite, officially named Willamette and originally known as Tomanowos by the Clackamas Chinook

It is the largest meteorite found in the United States and the sixth largest in the world. There was no impact crater at the discovery site; researchers believe the meteorite landed in what is now Canada or Montana, and was transported as a glacial erratic to the Willamette Valley during the Missoula Floods at the end of the last Ice Age (~13,000 years ago).

The Willamette Meteorite weighs about 34200 lb. It is classified as a type III iron meteorite, being composed of over 91% iron and 7.62% nickel, with traces of cobalt and phosphorus. The approximate dimensions of the meteorite are 10 feet tall by 6.5 feet wide by 4.25 feet deep. Most iron meteorites like Willamette have originated from the differentiated core of planetesimals or asteroids that collided with another object. Willamette has a recrystallized structure with only traces of a medium Widmanstätten pattern; it is the result of a significant impact-heating event on the parent body. The Willamette Meteorite contains higher concentrations of various metals that are quite rare in Earth's crust. For example, iridium, one of the least abundant elements in Earth's crust, is found in the Willamette Meteorite at a concentration of 4.7 ppm vs. having an average mass fraction of 0.001 ppm in crustal rock, thousands of times more concentrated than in the crust.
 * 1) Group: IIIAB meteorites.
 * 2) Structural classification: Medium Octahedrite.
 * 3) Composition: 91% Fe, 7.62% Ni, 18.6ppm Ga, 37.3ppm Ge, 4.7ppm Ir.
 * 4) Coordinates of find: 45.36667°N, -122.58333°W
 * 5) Total known weight: 14150 kg

IIICD meteorites

 * IIICD meteorite (IIICD): Ataxites to fine octahedrites, 10–23% Ni, 1.5–27 ppm Ga, 1.4–70 ppm Ge, 0.02–0.55 ppm Ir.

IIIE meteorites

 * IIIE meteorites (IIIE): Coarse octahedrites, 8.2–9.0% Ni, 17–19 ppm Ga, 3–37 ppm Ge, 0.05-6 ppm Ir, Ge-Ni correlation absent.

IIIF meteorites

 * IIIF meteorites (IIIF): Medium to coarse octahedrites, 6.8–7.8% Ni,6.3–7.2 ppm Ga, 0.7–1.1 ppm Ge, 1.3–7.9 ppm Ir, Ge-Ni correlation absent.

IVA meteorites

 * IVA meteorites (IVA): Fine octahedrites, 7.4–9.4% Ni, 1.6–2.4 ppm Ga, 0.09–0.14 ppm Ge, 0.4-4 ppm Ir, Ge-Ni correlation positive.

Gibeon meteorites
The meteorite was discovered by the Nama people and used by them to make tools and weapons.

In 1836 the English captain J. E. Alexander collected samples of the meteorite in the vicinity of the Fish River, Nico farm, and sent them to London. There John Herschel analyzed them and confirmed for the first time the extraterrestrial nature of the material.

Between 1911 and 1913, 33 fragments of the meteorite were collected in the vicinity of Gibeon and brought to the capital Windhoek. They weighed between 195 and 506 kg and were first stored, then displayed at Zoo Park as a single heap. In 1975 a public fountain displaying the meteorite fragments was planned, the pieces were removed and stored at Alte Feste, where two of the fragments were stolen, the fountain was erected in Post Street Mall, with two empty pillars for the missing fragments, since then, two more fragments were removed from the fountain, so that it displays only 29 today.

The fragments of the meteorite in the strewn field are dispersed over an elliptical area 390 km long and 120 km wide, with the core of this area situated near the village of Gibeon in Namibia's Hardap Region: about 100–150 different fragments have been collected over time, and additional pieces are found occasionally.


 * 1) Type: Iron meteorite.
 * 2) Name: NICO, Gibeon.
 * 3) Group: IVA.
 * 4) Structural classification: Fine octahedrite.
 * 5) Composition: 91.8% Fe; 7.7% Ni; 0.5% Co; 0.04% P; 2.4 ppm Ir; 1.97 ppm Ga; 0.111 ppm Ge.
 * 6) Country: Namibia.
 * 7) Region: Great Namaqualand.
 * 8) Coordinates 25°23' S 17°00'47" E.
 * 9) Observed fall: No.
 * 10) Fall date: prehistoric times.
 * 11) Found date: 1836.
 * 12) TKW: 26000 kg.
 * 13) Strewn field: Yes.

IVB meteorites

 * IVB meteorite (IVB): Ataxites, 16–26% Ni, 0.17–0.27 ppm Ga, 0,03–0,07 ppm Ge, 13–38 ppm Ir, Ge-Ni correlation positive.

Chinga meteorites
Ataxites exhibit no Widmanstätten patterns upon etching.

Composition: Meteoric iron 82.8%, 16.7% Ni in very rare kamacite lamella, inclusions: daubréelite. The total chemical composition is 82.8% iron, 16.6% nickel, and the rest mostly cobalt and phosphorus.

Fragments of the meteorite were found in 1913 by gold diggers in Tuva near the Chinge River after which it is named. Eventually, Nikolay Chernevich, a mining engineer supervising the gold diggers, sent thirty pieces, the heaviest of which was 20.5 kg, to the Russian Academy of Sciences in Saint Petersburg. Later expeditions have retrieved about 250 pieces with a total mass of 209.4 kg.

No impact structure was found. Studies from the fluvial deposits in which the meteorites were found estimate that it fell about 10,000 to 20,000 years ago. It burst during passage through the atmosphere, the pieces impacting on a glacier.


 * 1) Group: IVB-an, (2000), Iron-ung (2006).

Hoba meteorites
The Hoba iron meteorite shown on the right left no observable crater. This meteorite is the largest meteorite ever found and the largest piece of iron ever found. It is specifically an ataxite, which contains a significant fraction of nickel (about 84% iron and 16% nickel, with traces of cobalt), but not in taenite. It was estimated to weigh 66 tons when initially discovered.


 * 1) An ataxite iron meteorite belonging to the nickel-rich chemical class IVB.

Ungrouped meteorites

 * Ungrouped meteorites. This is actually quite a large collection (about 15% of the total) of over 100 meteorites that do not fit into any of the larger classes above, and come from about 50 distinct parent bodies.

Staunton meteorites
The Staunton meteorite was found near Staunton, Virginia in the mid-19th century. Six pieces of nickel-iron were located over a period of some decades, with a total weight of 270 lb.

Tamentit meteorites
The Tamentit Iron Meteorite was found in 1864 in the Sahara Desert, The Tamentit Meteorite, weighing half a ton, was discovered in the sands of the Algerian Sahara in 1864 near of Tamentit city and is currently on display at Parc Vulcania (Puy-de-Dôme), on loan from the Museum national d'Histoire naturelle de Paris.