Hammadah al Hamra 237 (HaH 237)

Hammadah al Hamra 237 (HaH 237) was discovered on October 18th, 1997 in the form of a single stone weighing 3.17kg in the Ash Shati' area of Libya. It was initially listed as a CH-Chondrite but after extensive studies of meteorites in this clan it was later reclassified into the CB3_b group. This meteorite has a Shock Rating of S3 and a Weathering Level of W2.

The CBb chondrite metal appears to have formed by a process very similar to that of the CH-Chondrites, but the CBb meteorite components experienced even less thermal alteration following their formation and are among the most primitive materials known to have formed in the solar nebula. (Campbell, Humayun & Weisburg, 2005)

Iron/Nickel (Fe,Ni) metal and chondrule silicates are the main components in HaH 237. These high temperature components are held together by shock melts consisting of droplets of dendritically intergrown Fe,Ni-metal/sulfide embedded in silicate glass, which is substantially more FeO-rich (30–40 wt%) than the chondrule silicates (FeO <5 wt%). Fine-grained matrix material, which is a major component in most other chondrite classes, is extremely scarce in HaH 237. (Meibom et al, 2004)

The Iron/Nickel (Fe/Ni) component in HaH 237 is considerably high at about 57% but the overall bulk composition of Iron (Fe) is 69.6 wt%. It also contains a very small amount (<1%) of CAI's (Calcium-Aluminium-Rich Inclusions) which measure a tiny 50-400µm. The characteristics of the CAI's in HaH 237 are inconsistent with an impact origin with these metal-rich meteorites. Instead it is suggested that the components in CB chondrites are pristine products of large-scale, high-temperature processes in the solar nebula and should be considered true chondrites. (Krot et al, 2001)

This specimen is part of the Meteorites Australia Collection (MA.07.0037).

Compositions of unzoned and zoned metal in the CBb chondrites
Hammadah al Hamra 237 and Queen Alexandra Range 94627. Andrew J. Campbell, Munir Humayunz, and Michael K. Weisberg. (1.47MB)

Refractory calcium-aluminium-rich inclusions and aluminium-diopside-rich chondrules in the metal-rich chondrites Hammadah al Hamra 237 and Queen Alexandra Range 94411. Alexander N. Krot, Kevin D. McKeegan, Sara S. Russell, Anders Meibom, Michael K. Weisberg, Jutta Zipfel, Tatiana V. Krot, Timothy J. Fagan and Klaus Keil. (3.39MB)

Volatile-poor Chondrules in CH Carbonaceous Chondrites: Formation at high ambient nebular temperature. Alexander N. Krot, Anders Meibom and Klaus Keil. (31.6kb)