CO Carbonaceous Chondrites

Northwest Africa 4967

Find: 2007
Carbonaceous chondrite (CO3.2)

History and physical characteristics: Two very dark stones that weigh a total of 689 g were purchased in Erfoud in August 2007. Some fusion crust remains, although aeolian processes have pitted and polished the stones to a shiny black luster.
Petrography (T. Bunch and J. Wittke, NAU): The interior is also very dark and structure is only recognizable in thin section. Consists of closely packed chondrules, CAIs and AOAs, matrix poor (vol% = 18). Olivine dominates the matrix together with pyroxenes, FeS, pentlandite, and metal. The stones are moderately weathered with low shock level.
Mineral compositions: Olivine, Fa2.1-63, Cr2O3 in type II PO olivine is 0.08 to 0.40 wt% with a peak at 0.26 wt%; FeO/MnO = 77-129 (N = 34).
Classification: Carbonaceous chondrite (CO3.2).
Type specimen: A total of 20.2 g is on deposit at NAU. The main mass holder is Cimala.

IDLocationDate Class. Mass (g)StateFaComments
NWA 2083Rissani, Morocco10/2003CO3144S1, W23.8-57.6 (photograph below)
NWA 2090Rissani, Morocco10/2003CO3875S1, W112.2-53.2 (photograph below)
NWA 2121Erfoud, Morocco2003CO3.224.5S1, W134.0-54.0 Cr2O3 in olivine = 0.05-0.18 wt. %; mean = 0.14 (photograph below)
NWA 2131Rissani, Morocco2003CO3596S2, W225.6-39.7-
NWA 2398Morocco2004CO3.1718S2, W218.6-49.7 Cr2O3 in olivine = 0.08-0.37 wt. %; mean = 0.28
NWA 2431Erfoud, Morocco2004CO3.336S2, W237.2-41.4 Cr2O3 in olivine = 0.06-0.10 wt. %
NWA 2633Erfoud, Morocco2004CO3.2600S2, W24.2-48.2 Cr2O3 in olivine = 0.07-0.23 wt. %; olivine FeO/MnO = 108-134
NWA 2647Erfoud, Morocco2004CO3.371S1, W238.4-40.2 Cr2O3 in olivine = 0.05-0.10 wt. %
NWA 2664Erfoud, Morocco2004CO3.678S2, W3 39.4 (37.9-39.8 N=17)-
NWA 4540 Erfoud, Morocco 2006 CO3.5 1310 S2, W2 38.3 FeO/MnO = 121
NWA 4542 Erfoud, Morocco 2006 CO3.6  S2, W3 36.7 -
NWA 4551 Erfoud, Morocco 2006 CO3.5 104 S2, W2 37.7-38.7 FeO/MnO = 110

Photographs of CO Chondrites

NWA 2083 © T. E. Bunch, 2004

NWA 2090. Source:

NWA 2121 (CO3.2) © T. E. Bunch, 2004