BENCUBBINITE
Bencubbinites are rare & aesthetic meteorites - only 20 have been reported.
Texturally, they are chondrites & are naturally dominated by
chondrules. However, they are very strange chondrites, because many of
the chondrules in bencubbinites are metallic iron.
The sample shown below is a slice from the Gujba
Meteorite, a bencubbinite that fell in northeastern Nigeria on 3 April
1984, but has only been subjected to scientific study since the early 2000s.
The Gujba Meteorite is dominated by metallic
chondrules. Gujba's metal chondrules are slightly elongated spheroids
containing iron and a little nickel. The large, light-colored rounded
structures are silicate chondrules. Published research has shown that the
silicate chondrules consist of forsterite olivine or pyroxene plus feldspathic
glass. The matrix surrounding the large metal & silicate chondrules
is principally composed of small silicate chondrule fragments.
Very few meteorites can be classified as
bencubbinites, or CB chondrites. The details of their origin are not yet
clear, and several hypothesized formation mechanisms have been proposed.
Chondrules
of the Gujba Meteorite have been dated to 4.5627 billion years.
Bencubbinite slice, 4.6 x 3.8 cm in size.
Bencubbinite
Bencubbinite
(More info. on the
Gujba Meteorite)
The above information is mostly synthesized from:
Rubin et al. (2001) - Gujba: a new Bencubbin-like
meteorite fall from Nigeria. 32nd Lunar and Planetary Science
Conference, March 12-16, 2001, Houston, Texas. Abstract 1779.
Weisberg et al. (2002) - Gujba and origin of
Bencubbin-like (CB) chondrites. 33rd Lunar and Planetary Science
Conference, March 11-15, 2002. Abstract 1551.
Krot et al. (2005) - Young chondrules in CB chondrites
from a giant impact in the early solar system. Nature 436:
989-992.
Weisberg et al. (2006) - Discovery of coesite and
significance of high pressure phases in the Gujba CB chondrite. 37th
Lunar and Planetary Science Conference, March 13-17, 2006. Abstract
1788.
Specimen acquired through the generosity of Lee &
Mary Ellen St. John.