CB
Name
*click on the Name for more information
Structure Class
Carbonaceous chondrites
Chemical Class
CBa
Country
United States of America
Year found
2021
Mass
550 g
[Museum Collection]
(1) 0.21g (2) 0.20g (3) 0.18g (4) 0.13g
History: On the 6 February 2021, Todd Parker and Robert Ward were searching for gold with metal detectors on Grapevine Mesa, east of Meadview, Mohave County, Arizona. Parker detected a signal, which turned out to be three pieces weighing 252.5 g of a metal-rich meteorite. Together, they recovered 550.3 g in a 2 × 2 m area. Physical characteristics: Exterior of the stones are rusty with patches of fusion crust. Interior of a 4 × 4.5 cm slice shows rounded to angular silicate fragments (to 1 cm) hosted by rounded to anhedral metal grains to 0.7 cm. Metal constitutes 69 areal% of the slice. The metal sizes, shapes, and distribution closely resemble that of Bencubbin. Petrography: A 2 × 1.5 cm polished section shows metal grains composed of micron-sized polycrystalline kamacite containing an abundance of micron-sized troilite blebs and stringers (~1 areal%). Silicates consist of magnesian nonporpyritic silicate fragments with a cataclastic texture. White orange-stained silicate fragments separated by black opaque material hosting sub-mm-sized silicate fragments and rounded troilite and kamacite blebs. Thin terrestrial oxide veins are present around the metal grains. Geochemistry: Oxygen isotopes (K. Ziegler, UNM): Seven fragments analyzed by laser fluorination gave δ18O = 6.949, 5.840, 4.998, 4.541, 5.968, 5.283; δ17O = 3.467, 2.239, 2.456, 1.485, 2.409, 2.091; Δ17O = -0.202, -0.845, -0.183, -0.913, -0.742, -0.699 (linearized, all per mil, TFL slope = 0.528). Average of the seven analyses gives δ18O = 5.596±8.848, δ17O = 2.358±0.646, Δ17O = -0.597±0.323. EPMA (L. Garvie, ASU): Low Ca pyroxene Fs3.17±0.79Wo1.88±2.62 (n=4), Al2O3 = 0.4 to 3.2, TiO2 = 0.1 to 0.2, and Cr2O3 = 0.4 to 0.7 (all wt%); High Ca pyroxene Fs3.37Wo38.45 (n=1), Al2O3 = 7.9, TiO2 = 1.0, and Cr2O3 = 1.5 (all wt%); Olivine Fa3.67 and 4.71; Metal (wt%) Ni = 7.03±0.70, Co = 0.33±0.04, Cr = 0.20±0.09, and P = 0.33±0.04. Classification: The meteorite mineralogically matches that of the subgroup A (CBa) Bencubbin-like carbonaceous chondrites. The oxygen isotopes follow on an extension of the current bencubbinite field. Specimens: Largest mass of 61 g is with Robert RWard. 21 g and a polished mount at ASU.
*click on the Name for more information
Structure Class
Carbonaceous chondrites
Chemical Class
CBa
Country
Nigeria
Year found
1984
Mass
100 kg
[Museum Collection]
(1) 41.9g (2) 26.6g (3) 13.7g (4) 11.4g
(5) 11.3g (6) 9.6g (7) 9.3g (8) 7.1g
(9) 6.5g (10) 3.8g (11) 3.7g (12) 3.1g
(13) 3.1g (14) 2.6g (15) 2.2g
A conical meteorite fell in a corn field near the village of Bogga Dingare after a bright fireball was witnessed moving west to east and an explosion was heard. The local people hammered the meteorite into many pieces, and most of the material was dispersed. The original mass is unknown, although secondhand reports indicate that it had a volume of ~20 000 cm3, and thus a mass of ~100 kg. Material that almost certainly came from this fall has been sold in the last few years elsewhere in Nigeria, with claims that the specimens were new finds. A preliminary description of the meteorite appears in Islam and Ostaficzuk (1988). Description (L. Karwowski, USil, based on the original mass): contains metal nodules, 1.5–8 mm in diameter, and silicate nodules 1–15 mm in diameter with fan-like aggregates of pyroxene; 60% of nodules are metal. Description and classification (A. Rubin and G. Kallemeyn, UCLA, based on a 282 g fragment purchased in 2000 near the village of Gidan Wire in Kaduna state): consists of large metal nodules containing variable amounts of troilite, and cryptocrystalline silicate spheroids; silicates include pyroxene (Fs1–2Wo1–3) and rare olivine (Fa3); siderophile abundance pattern in metal is similar to that of Bencubbin; shock stage, S2; weathering grade, W0. Oxygen isotopes (R. Clayton, UChi): light-colored silicates, δ17O = -2.19·, δ18O = +0.53·; dark-colored silicates, δ17O = -1.78·, δ18O = +0.98·. Specimens: 12.2 kg, mostly disintegrated, UMaid; 815 g, MZP; type specimen, 64 g, UCLA; remainder of 282 g mass, Twelker.