USA | Southwest Meteorite Laboratory

Portales Valley

Portales Valley is an extra-ordinary chondrite. The classification H6 based upon the olivine fayalite, is an over simplification of a complex meteorite. More appropriately classified an H7, metallic-melt breccia with affinities towards the metal-rich primitive achondrites, (MaPS 40). Many of the meteorites recovered from this fall are metal-rich containing up to 50% metal arranged as a fine octahedrite. It is an unprecedented ordinary chondrite.

Meteoritical Bulletin #83 report: After detonations were heard and smoky trails seen in the sky, a shower of meteorites landed near Portales, New Mexico. 53 objects have been recovered, with a total mass of 71.4 kg. The largest pieces weighed 16.5 kg (witnessed to fall by Nelda Wallace and Fred Stafford), 17.0 kg (found by Elton Brown), and at least nine others over 1 kg. A 530 g fragment went through the roof of Gayle Newberry’s barn and embedded itself in a wall, indicating a trajectory west to east. The elliptical strewn field is approximately 7.7 ´ 2 km, trending N60–65ºE, although recent reports may extend this somewhat. Mineralogy (D. A. Kring, J. D. Gleason, and D. H. Hill, UAz ): olivine, Fa19.3 ±0.4; pyroxene, Fs17.2 ±0.3 Wo1.36±0.27; kamacite contains 0.55 ± 0.03 wt% Co; compositions indicate H-chondrite affinity; olivine indicates shock stage S1, plagioclase indicates S2–S3, and abundant opaque shock veins suggest S3 or higher (discrepancies may be due to annealing). Macroscopic description (D. A. Kring, UAz ): Some individuals are crosscut by an unusually high number of metal-rich shock veins, and some specimens are composed dominantly of metal. These metal-rich samples appear to be large single veins, or pockets of metal produced by intersecting veins. Angular chondritic clasts may have moved a few millimeters along metal-rich veins. Etching of centimeter-sized metal areas reveals a fine Widmanstätten pattern, bandwidth = 0.02 to 0.81 mm (average 0.32 mm). The composition of kamacite in metal-rich regions is the same as metal in chondritic areas (0.56 ± 0.05 wt% Co). The source of the metal in the shock veins appears to be the H-chondrite host, which is depleted in its normal complement of metal (4.4% rather than 15–19%). Specimens: type specimen, 49 g, and thin section, UAz; 16.5 kg mass purchased by consortium including FMNH, SI, UCLA, and UNM. 17.0 kg mass with finder; much of remaining material is being sold by commercial meteorite dealers.

Red Rock

One mass of 47.6kg was found and purchased by the University of California, Los Angeles, Met. Bull. 64, Meteoritics, 1984, 19, p.54, A.L.Graham et al., Cat. Met., 1985, p.300. Classification and analysis, 7.71% Ni, 21.6 ppm Ga, 41.8 ppm Ge, 2.1 ppm Ir, D.J.Malvin et al., GCA, 1984, 48, p.785. Further analysis, M.Hoashi et al., Chem. Geol., 1992, 98, p.1.

Richfield

A stone of 40.8kg was found while terracing a grain field; mineralogy and classification (A.Rubin, Univ. of California, Los Angeles), olivine Fa26.1, TL data (P.Benoit, Univ. of Arkansas), J.N.Grossman, Met. Bull. 80, MAPS, 1996, 31, p.A176. Noble gas data and exposure ages, E.Polnau et al., MAPS, 1996, 31, p.A109 (abs.). Mineral analysis, shock classification, TL and noble gas data; an unequilibrated genomict chondrite breccia consisting mainly of light recrystallized clast and dark clasts exhibiting significant silicate darkening, A.E.Rubin et al., MAPS, 1996, 31, p.925. Physical properties, G.J.Flynn et al., LPSC, 1999, 30, abs. #1073. ITL data, P.H.Benoit et al., MAPS, 2002, 37, p.793. Relative M

Roosevelt County 102

Listed, with classification and mineral analysis, J.N.Grossman, Met. Bull. 84, MAPS, 2000, 35, p.A199.

Roosevelt County 089

A single cube-shape stone of 1615g was found by N.Widener in the Roosevelt County area; listed, Met. Bull. 78, Meteoritics, 1995, 30, p.795. Classification and mineral analysis, contains a large troilite grain with unusual and complex weathering products, G.K.Benedix et al., Meteoritics, 1995, 30, p.788.

Roundsprings

A stone of about 6 kg was found in a pasture by Jim Steward and used as a doorstop and to make car repairs; classification and mineral analysis (M.E.Zolensky, NASA JSC; A.Rubin, Univ. of Calif., Los Angeles), J.N.Grossman, Met. Bull. 82, MAPS, 1998, 33, p.A221.

Landes

A 69.8kg individual was plowed up in a hillside cornfield, about 1 mile E of the Landes Post Office, about 35 to 40 years before being recognized as a meteorite, Met. Bull. 51, Meteoritics, 1972, 7, p.225. Reported, T.E.Bunch et al., Meteoritics, 1971, 6, p.253 (abs.). Silicate mineralogy, Odessa type, T.E.Bunch et al., Meteoritics, 1972, 7, p.31. Structurally anomalous, analysis of metal, 6.31% Ni, 88.7 ppm Ga, 414 ppm Ge, 2.9 ppm Ir, J.T.Wasson, Meteorites, Springer-Verlag, 1974, p.297. Major, minor and trace element composition of silicate inclusions, R.W.Bild, GCA, 1977, 41, p.1439. I-Xe dating of silicate inclusions, S.Niemeyer, Meteoritics, 1977, 12, p.331 (abs.); GCA, 1979, 43, p.843. Ar-Ar age of silicate inclusions, 4.48

Monahans

One mass of 27.9kg was found 7 miles S and 1 mile E of Monahans, A.D.Nininger, Pop. Astron., Northfield, Minnesota, 1939, 47, p.212, M.H.Hey, Cat. Met., 1966, p.312. Description, with analysis, 10.88% Ni, H.H.Nininger, Pop. Astron., Northfield, Minnesota, 1939, 47, p.268 (M.A.7-376). Description and analysis of the iron shale, 4.99% NiO, J.D.Buddhue, Pop. Astron., Northfield, Minnesota, 1939, 47, p.271 (M.A.7-377). Description of structure, H.J.Axon and P.L.Smith, Min. Mag., 1972, 38, p.736. Classification and analysis, 10.6% Ni, 8.9 ppm Ga, 127 ppm Ge, 14 ppm Ir, J.T.Wasson, GCA, 1969, 33, p.859. Nitrogen abundance, E.K.Gibson and C.B.Moore, GCA, 1971, 35, p.877. Coordinates, description, V.F.Buchwald, Handbook of Iron Meteorites, Univ. of California, 1975, p.832. Nitrogen isotopic composition, I.A.Franchi et al., GCA, 1993, 57, p.3105, C.A.Prombo and R.N.Clayton, GCA, 1993, 57, p.3749. Determination of metallographic cooling rate, H.Haack and K.L.Rasmussen, LPSC, 1996, 27, p.477 (abs.); see also, K.L.Rasmussen et al., MAPS, 2001, 36, p.883. Ion probe analysis of carbon and nitrogen distribution in taenite, N.Sugiura, MAPS, 1998, 33, p.393.

Lamont

Found along a fence row and placed in a rock garden for many years before it was recognized and authenticated.

Ioka

A weathered stone of 31.5kg was plowed up and recognized as meteoritic in 1956, A.L.Graham et al., Cat. Met., 1985, p.175. Analysis, 20.77% total Fe, E.Jarosewich, GCA, 1966, 30, p.1261. Olivine Fa23, B.Mason, GCA, 1963, 27, p.1011. Trace element concentrations, C.M.Binz et al., GCA, 1976, 40, p.59. Petrologic subtype 3.5 based on ITL data, P.H.Benoit et al., MAPS, 2002, 37, p.793.