The Consummation of a New Iron Group—IIG

The five iron meteorites displayed on this page, which constitute the newly designated group IIG, sharing the charateristics of low-Ni, high-P hexahedrites, are presented here courtesy of the Dr. J. Piatek Collection.

Tombigbee River

standby for bellsbank photo

An iron mass was found in 1859 in western Alabama, USA, followed in subsequent years by the recovery of five additional masses. The six iron masses had a combined weight of 43.8 kg. In 1867, an extensively oxidized 3.63 kg mass was plowed up 250 km east of the Tombigbee River find. Although the meteorite has been given the name Auburn, it is commonly considered to be a transported piece of Tombigbee River. Tombigbee River was initially classified as an ungrouped iron, but since it was shown to have similar compositions to two later found iron meteorites, La Primitiva and Bellsbank, these three meteorites became known as the Bellsbank Trio. The photo above shows a 117.2 g slice of this rare fall, acquired from the United States National Museum, Smithsonian Institution by Dr. J. Piatek. > read more

La Primitiva

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Between 1888 and 1911, six iron masses weighing together 27.4 kg were found in and around the nitrate plants in the Tarapaca Region of Chile. The photo above shows a 74 g partial slice, acquired from Sergey Vasiliev—SV Meteorites by Dr. J. Piatek.


standby for bellsbank photo

A 38 kg iron mass was found just below the surface in Cape Province, South Africa, in 1955. The photo above shows a 22.2 g partial slice, acquired from the United States National Museum, Smithsonian Institution by Dr. J. Piatek.


standby for twannberg photo

A 15.91 kg iron was found in May 1984 by M. Christen in a field on Twann Mt. (Twannberg), Switzerland, in association with glacial till transported by the Rhône glacier during the last ice age (Hofmann et al., 2009). A 2.2 kg paired mass was discovered by M. Jost in the attic of an old house in the village of Twann in January 2000. In 2005, a third mass was discovered as part of a rock collection in the Natural History Museum Bern, which previously belonged to the Schwab Museum, and which was incorrectly labeled as hematite. In 2007 three more paired masses were found in the Twannbach canyon, and more recently many other transported masses were recovered near Twannbach River and Gruebmatt. Beginning in 2015, numerous masses have been recovered at Mont Sujet plateau. These are non-transported masses in their original fall location, delimiting a strewn field of over 4.5 km in a direction ENE to WSW (Hofmann et al., 2016). These recent recoveries raise the TKW to ~70 kg in ~550 individual pieces (Smith et al., 2016). The present total recovered weight is in stark contrast to the estimated ~30 million kg mass of a 20-m-diameter meteoroid calculated to have fallen 165 (±58) t.y. ago (Smith et al., 2016). With the discovery of Twannberg and its observed genetic relationship with the three irons presented above, the iron grouplet became known as the Bellsbank Quartet. The photo above shows a 74 g slice from the first discovered mass, acquired from the Jim Schwade Collection by Dr. J. Piatek.


standby for guanaco photo

A single 13.1 kg iron meteorite was found in Antofagasta, Chile in 2000. Guanaco became the requisite fifth recognized member of this Ni-poor (4.3%), schreibersite-rich iron group (the Bellsbank Quintet), and therefore, John T. Wasson has proposed that this new group be given the designation IIG. Shown in the photo above is a 310 g slice acquired from Rodrigo Martinez—Atacama Desert Meteorites by Dr. J. Piatek. > read more

© 1997–2017 by David Weir