Pallasite with Dark Olivine
Item: 6.1 Dimensions: 50 x 57 x 38 mm Weight: 340.6 g
Provenance: Field Museum of Natural History, Chicago
This is a unique pallasite. It is known for its large, opaque olivine which almost look black against the metalic matrix.
Partial/complete: Block
Cube: ~15mm x 15mm x 15mm ≈ 15mm3

Ahumada

Country: Mexico
Region: Chihuahua
Found: 1909
Group: Stony-Iron
Type: Pallasite
Class: PAL
Total known weight: 52.6kg

A mass of 116lb was found 60 miles E of Ahumada, M.H.Hey, Cat. Met., 1966, p.9. Described, O.C.Farrington, Field Mus. Nat. Hist. Geol. Ser., 1914, 5, (178), p.1. Cooling rate and olivine composition, Fa11.6, P.R.Buseck and J.I.Goldstein, Bull. Geol. Soc. Amer., 1969, 80, p.2141. Analysis of metal, 8.0% Ni, 21.4 ppm Ga, 49.0 ppm Ge, 0.057 ppm Ir, J.T.Wasson and S.P.Sedwick, Nature, 1969, 222, p.22. Classification and analysis of metal phase, main group pallasite, E.R.D.Scott, GCA, 1977, 41, p.349. Study of olivine-metal texture, E.R.D.Scott, GCA, 1977, 41, p.693. Mineralogy and petrology, contains pyroxene, P.R.Busek, GCA, 1977, 41, p.711. Chemical composition of olivines, J.V.Smith et al., J. Geophys. Res., 1983, 88 (suppl.), p.B229. Nitrogen isotopic composition of metal and silicate, C.A.Prombo and R.N.Clayton, GCA, 1993, 57, p.3749; see also, LPSC, 1984, 15, p.655 (abs.); LPSC, 1983, 14, p.620 (abs.). Oxygen isotopic composition, R.N.Clayton and T.K.Mayeda, GCA, 1996, 60, p.1999.