New Baltimore - New Leipzig 897
New Baltimore is structurally unique. Chemically, it is consideration in the matter," wrote Buckwitz to the anomalous, too, in combining typical group IliA Ga-Ge-lr Secretary of the Smithsonian Institution on February 6th, ratios with significantly lower P- and Ni-values. Compare, 1937. The discoverer was "a man of poor circumstances, for example, with Wabar and Norfolk. Previous suggestions located in the worst drought area in the State of North by Merrill (1923d) and Stone (1932) that New Baltimore Dakota" with an invalid wife, confined to her bed with was a paired fall with Mount Joy and Pittsburg were already arthritis. "The discovery of this meteorite on my farm and disproved by Henderson & Perry (1958: 368); their conclu the sale of it is a blessing from Heaven for me and I thank sion is fully supported here. God for it." The meteorite has been briefly mentioned by A.D. Specimens in the U.S. National Museum in Washington: Nininger (1937), but it is not described. I ,470 g end piece (no. 710, 13 x 8 x 3 em) 748 g piece with artificial cleavage fracture (no. 710, 10 x 7 x 3 em) COLLECTIONS 167 g polished slice (no. 710,11 x 8 x 0.5 em) 600 g individual, loose kamacite grains (no. 710, ranging from 7 to Washington (17 .9 kg), Chicago (558 g), Calcutta 133 g) (183 g), London (19 g), Tempe (19 g). 50 g oxide-shales (no. 71 0)
ANALYSES No analysis has been performed. From an examination New Leipzig, North Dakota, U.S.A. of the structure I would expect 6.7±0.2% Ni and 46°22'N, 101 °57'W; 750 m 0.2±0.04% P with Ga-Ge-Ir concentrations characteristic for group I.
Coarse octahedrite, Og. Bandwidth 2.6±0.5 mm. Neumann bands. HV 205±10. DESCRIPTION Group l,judging from the structure. About 6.7% Ni and 0.2% P. The meteorite is a beautifully sculptured, angular mass with the overall cimensions of 30 x 15 x 12 em. On most of HISTORY the surface it is covered by well developed regmaglypts, A mass of 20.0 kg was found in 1936 by Daniel ranging from 1-3 em in diameter and 5-10 mm deep. Buckwitz, Jr., on his farm on Route I, near New Leipzig, in Between the individual pits there are rounded knobs and Grant County. The corresponding coordinates are given ridges which serve to give the surface a very irregular above. Buckwitz notified a senator from North Dakota outline. The knobs may attain dimensions of 7 x 2 x 2 em
Figure 1249. New Leipzig (U.S.N.M. no. 121 0). The main mass now Figure 1250. New Leipzig (U.S.N .M. no. 121 0). A coarse octahe weighs 17.0 kg after an end piece has been removed (right). drite. Secondary grain growth has somewhat eliminated the previous Regmaglypts are prominent. Scale bar approximately 4 em. S.l. Widmanstiitten pattern. Deep-etched. Scale bar 15 mm. S.I. neg. 1631A. neg. 1658. who, in turn, established connections with the U.S. or 3 x 2 x 2 em. A few deep pits indicate where troilite was National Museum, and in 1937 the mass was purchased for removed by ablational melting; the largest has an aperture $150. "It is deeply gratifying for me to hear that you found of 15 x 30 mm and is 20 mm deep. Near the middle of the the specimen to be of such type that you could pay me this oblong mass, a conspicuous, straight 6 em long crevice amount for it. I was confident that you would do the right forms a 2 em deep and 3 mm wide and partly undercut thing and I assure you that I greatly appreciate your kind scar; the incision was apparently formed by ablational 898 New Leipzig
melting of a troilite-schreibersite aggregate. One face, which recovery has taken place here without visible alteration of may be termed the rear face during flight, is rather plane the structure (hardness curve type II). and covered with large shallow regmaglypts, typically 2.5-5 em across and 0.5 em deep. The oxidic fusion crust is Etched sections dis~ay a coarse Widmanstiitten struc ture of straight, short (w ~ 10) kamacite lamellae with a width of 2.6±0.5 mm. Late grain growth has eliminated many of the straight lamella boundaries and created more or less equiaxial grains, 3-15 mm across. Taenite and plessite may, therefore, be found inside uniformly oriented kamacite grains and, in addition, along grain boundaries. The kamacite has subboundaries decorated with 0.5 J.1 phosphides, and Neumann bands are well developed. The microhardness is 205±10, corresponding to a slightly work-hardened, unannealed kamacite matrix. Taenite and plessite cover little more than 1% by area, mostly as dt:generated comb plessite fields , 1-2 mm across. Acicular plessite with 2-5 J.1 wide kamacite needles is also present. The taenite rims are tarnished due to carbon in Figure 1251. New Leipzig (U.S.N.M. no. 1210). Rounded kamacite solid solution. grain s with schreibersite at grain boundaries and Neumann bands in the interior. Scale bar 500 IL· Schreibersite is common as 2 x 0.3 mm skeleton crystals and lamellae and as 50-100 J.1 wide grain boundary precipitates. Rhabclites are ubiquitous, both as 5-20 J.1 preserved as paper-thin coatings which, in places, cover prismatic rods and as a second generation of 1 J.1 crystals. 1-10 em 2 • It is rust colored from incipient corrosion , and in Where the ablating surface happened to pass a larger some places the weathering has proceeded to create schreibersite crystal this melted out in advance, and its 0.1-0.5 mm thick, terrestrial oxides. cavity was immediately filled, at least partially, to a depth A section through one of the knobs discloses the of 4 or 5 mm with metallic fusion crust. well-preserved heat-affected a 2 zone, ranging from 14.5 mm in thickness. A section through the massive part of the meteorite near one end showed a thickness of
Figure 1253. New Leipzig (U.S.N.M. no. 1210). Deformation has \ brecciated the schreibersite crystal and created numerous cracks along cubic cleavage planes of the kamacite. The fissures are now partially recemented by terrestrial lin10nite. Etched. Scale bar Figure 1252. New Leipzig (U.S.N.M. no. 1210). The degenerated 200 !J.. acicular plessite field was formerly situated in an a- a grain boundary, but due to grain growth it is now entirely within one grain. Etched. Scale bar 300 IL· No other minerals were positively identified in the sections, but troilite-daubreelite and graphite-cohenite are almost certainly present, judging from the exterior ablation 1-2 mm. It may safely be concluded that little of the mass grooves and from the general structure. has been lost by weathering, the highest reduction observed being of the order of 1 mm, and this only locally. The The meteorite displays several intercrystalline fissures, microhardness of the a 2 zone is 19 5± 10 . It decreases to a 10-100 J.1 wide . They are, of course, now partially filled minimum of 160±10 at the transition from a 2 to a because with corrosion products, but it appears that at least some of New Leipzig - New Mexico 899
{ ' ' New Leipzig is a coarse octahedrite structurally related to Campo Del Cielo, Gladstone and Seel:'isgen, and it will t. ll1 ~ probably turn out to be a normal member of group I. ,!;',/
I . •_ ·f';<·,.·•. • Specimens in the U.S. National Museum in Washington: .._ ·< .,_ ' 17.0 kg main mass with 12 x 5 em polished section at one end (no. 1210,26 xIS x 12 em) ~~.. \ 0:, • • J , L 341 g part slice (no. 1210, 12 x 6 xI em) 558 g slice (no. 121 0) > , ,~ ,· . -~---r<> ' ...... 0 h• ' -'"--"--
New Mexico, U.S.A.
' ' ,·· .., An Indian ax of 130 g was found in a ruin in New Mexico and in / !935 was re cognized as of meteoritic origin (Nininger & Nininger I 1950: 78). No particulars of the origin or discovery site are known. Figure 1254. New Leipzig (U.S.N.M. no. 1210). Heat-affected The material which is in Tempe (No. 511.1, 126 g), is an elongated a zone which has penetrated from above until it was stopped 2 ax-shaped mass, measuring 65 x 25 x 15 mm. At one end is a cutting (temporarily) by the poor heat-conduction across a cracked grain boundary. Etched. Scale bar 300 J.L. them were preatmospheric. For example, the regular smooth ingression of the a 2 zone is abruptly stopped at an open grain boundary at a depth of only 1.5 mm, while the zone in similar positions elsewhere is 3-4 mm thick. It seems that there was no heat conduction across this boundary when the meteorite entered the atmosphere, and the only explanation for this must be the fact that the grain boundary was already open. In other places grain bound aries occur with severely brecciated schreibersite and Figure 1255. New Mexico (Tempe no. 511.1). An Indian ax of troilite, the fragments of which are 5-50 J.1 across. They are 130 g. Apparently the owner acquired a single finger-shaped lamella recemented to a solid matrix by terrestrial limonite, but it of a coarsest octahedrite and, with minimum of work, shaped it to the appropriate form. Smoked with NH 4 Cl. Scale bar 1 em. S.I. appears that the material once loosely filled the fissures. neg. 488A. The violent event that produced the fissure in the metal and fragmented the minerals, also displaced the two sides of the fissure slightly, as proved by the presence of bent Neumann bands near the fissure.
Preatmospheric, intercrystalline fissures in iron meteor ites are much more common than generally realized. They probably originated at the time of the cosmic event that created the Neumann bands, and they have, therefore, normally existed for millions of years. The presence of preatmospheric fissures - both in the grain interior and along grain boundaries - makes it somewhat easier to understand why seemingly massive and very strong mater ials, such as iron-nickel meteorites, frequently break up in the atmosphere and form showers. In calculations of reentry decelerations, it is unrealistic to insert experimental test values of massive iron-nickel material; the bulk strength of most iron meteorites is significantly lower than the ideal values because the meteorites contain numerous inclusions and, in addition, numerous cracks from previous shock events. The presence of microcracks in the metal and in the minerals also serves to explain the readiness with which a terrestrial corrosion attack penetrates to a depth of several Figure 1256. New Mexico. Section through Figure 1255. The centimeters in an apparently massive and otherwise well material is a single kamacitc crystal. Superficial working has bent preserved iron meteorite. the Neumann bands. Deep-etched. Scale bar 3 mm. S.I. neg. 488. 900 New Mexico -New Westville edge, at the opposite end is a (recen tly) cut and polished surface. An octahedral planes. On sections it is seen how intercrystalline examination of the structure discloses only a rather pure kama cite corrosion penetrates along the phosphide lined grain bound matrix, without Widmanstiitten structure and without any meteor itic minera ls, such as taenite, schreibersite, troilite and cohenite. aries and how the a-constituent of the plessite phase is Slightly bent Neumann bands are, however, locall y present along the particularly rapidly attacked. No fusion crust and no surface. In a few places on the uncut surface there are signs of sligh t heat-affected a 2 zones are preserved. The mass has prob cold work with overfolded kamacite, but there are no indications that the ax should have been produced by forging or excessive cold ably lost a few centimeters of its original skin by corrosion. work. Etched sections display a fine octahedrite structure of It appears that on some occasion the Indian had acquired a single finger-shaped lamella from one of the coarsest octahedrites of the straight , long (~ ~ 40) kamacite lamellae with a width of American Southwest. Since such individual lamellae may from the 0.42±0.06 mm. The kamacite is hatched and of the variety beginning have shapes suggestive of an ax, the Indian needed only which usually is ascribed to a shock transformation above apply very little additional work, such as grinding, to finish his tool. a E As possible so urces, such irons as Navajo, El Burro and Sandia 130 k bar, from via back to a-structure. The hardness is Mountains may be considered. The possibility that the material correspondingly high but somewhat irregular, 285±30. should be from some hexahedrite (Hey 1966: 340) appears, from Plessite covers about 50% by area as comb and net plessite, structural considerations, much less likely. as cellular "Gibeon" plessite, and as duplex a+ 'Y fields of varying fineness. A typical field will show a yellow taenite rim (HV 290±15) followed by a light-etching martensitic New Westville, Ohio, U.S.A. transition zone (HV 360±20). Farther inwards come dark 39°50'N, 84°47'W; 350m etching martensite (HV 350±20) and finally, for example, a duplex a+ "f mixture (HV 250±20). It is rather unusual fine octahedrite, Of. Bandwidth 0.42±0.06 mm. e-structure. that the duplex structure is softer than the adjacent HV 285 ±30. kamacite lamellae , and the explanation is not obvious. Group IVA . 9.40% Ni, 0.47% Co, 0.14% P, 2.40ppm Ga, 0. 139 ppm Ge , 0.55 ppm Jr. Schreibersite is common as 5-25 J.1 wide grain boundary veinlets. Occasionally they increase to I 00 or 200 J.1 in HISTORY thickness, and they may then include a tiny, monocrystal A mass of 4.8 kg was found in 1941 in a field near line, troilite nodule. Schreibersite is also common as 2-15 J.1 U.S. 40, about 3 km east of the Ohio-Indiana state line near irregular blebs inside the plessite. The phosphide concentra- New Westville, in Preble County. It was acquired by S.H. Perry and donated to the U.S. National Museum where it was thoroughly described with several photomicrographs by Henderson & Perry (1946).
COLLECTIONS Washington (3,318 g), Madrid (343 g), Moscow (228 g), Chicago (206 g), Calcutta (203 g), Harvard (68 g).
DESCRIPTION The overall dimensions of the oval mass were 16 x 10 x 6 em, and the recovered weight was 4.8 kg. It is heavily corroded and continues to deteriorate under museum conditions of normal dry air conditioning. It is covered with 1-10 mm thick terrestrial oxides which easily spall off; Figure 1257. New Westville (Moscow). A fine octahedrite of group and the Widmanstatten structure is clearly seen upon the IV A. It is corroded, particularly along schreibersite-filled grain surface because there is a preferential attack along the boundaries. Deep-etched. Scale bar 20 mm. S.l. neg. 36673.
NEW WESTVILLE - SELECTED CHEMICAL ANALYSES percentage ppm References Ni Co p c s Cr Cu Zn Ga Ge Ir Pt Henderson & Perry 1946 9.41 0.61 0.10 Dyakonova 1958a 9.45 Jarosewich 1968, pers. comm. 9.38 0.34 0.18 Schaudy et al. 1972 9.36 2.40 0.139 0.55 New Westville- N'Goureyma 901
Koakourou and Djenne. Unfortunately, no details of the ~ fall have been published and even the locality is given differently by Meunier and Cohen. The mass was said to have been recovered from a one meter deep hole in clay, ~ but it is not known how rapidly it was recovered . The mass was acquired by H. Minod (Comptoir Mineralogique et Geologique, Geneva), who cut and distributed it in 1900 ~.. :v. ... - and following years at a price of 2-3 Francs per gram. The '~~ meteorite was briefly described by Meunier (1901 ), then much more detailed and with excellent photographs by Cohen (1901a). A summary with all the essential observa tions was printed in English (Cohen 1903d). Goldschmidt ,• (1930) found 2 ppm platinum metals, and Goldschmidt & Peters (1932) found 5 ppm Pd and 1 ppm Au. Cobb (1967) found 0.2 ppm Au. El Goresy (1965) observed chal .... ~ -...;; copyrrhotite as an accessory mineral and gave a micrograph Figure 1258. New Westville (U.S.N.M. no. 1412). Shock-hatched of the metallic fusion crust. Ramdohr (1967) gave a similar kamacite of high hardness (285 Vickers). Various plessite types. micrograph and discussed the fusion crusts on meteorites in Fissured schreibersite at grain boundaries. Etched. Scale bar 400 p.. general. Buchwald (1966) briefly discussed two micro (Perry 1950: Volume 6.) graphs that suggested an anomalously high cooling rate for N'Goureyma. Axon et al. (1968), who presented similar tion is in harmony with the analytically determined average photographs, proposed that such a structure might be the of0.14% P. result of rapid reheating plus rapid cooling of an original Troilite blebs, 0.2-3 mm in diameter, occur with a monocrystalline meteorite with normal Widmanstatten pat 2 frequency of about one per 15 cm . Only small ones were tern. Vilcsek & Wanke (1963) estimated the exposure age present in the polished sections, and they were all mono to be 215±20 million years. liimmerzahl & Zahringer crystalline. Several of the troilite nodules are developed (1966) found 280±190 million years, while Chang & Wanke around 0.1-0.5 mm angular, cubic chromite crystals, and (1969) found 200±20 million years. The amount of noble the whole aggregates are surrounded by 20-50 JJ. thick, gases was determined by Hintenberger & Wanke (1964). disc on tin uous schreibersite precipitates. Daubreelite was not observed. New Westville is a weathered fine octahedrite related to Mart and Chinautla, but a little different in the details of the structure, indicating a slightly different story after the initial cooling period. Chemically, it is a typical group IV A iron.
Specimens in the U.S. National Museum in Washington: 2.63 kg half mass (no. 1412,10 x 10 x 6 em) 385 g cndpiece (no. 1412, 9 x 5.5 x 2 em) 200 g small sections and oxidi ze d fragments (no. 1412)
N'Goureyma, Massina, Mali Approximately 13° 51'N, 4 °23'W
Anomalous, polycrystalline, troilite-rich iron. Martensitic-plessitic matrix. HV 215±15. Anomalous. 9.41 % Ni , 0.56% Co, 0.05% P, 0.6% S, 0.07 ppm Ga , 0.02 ppm Ge, 0.6 ppm lr. The date of fall is questionable.
HISTORY A mass of 37.7 kg was said to have fallen June 15, Figure 1259. N'Goureyma. The main mass before cutting, seen from 1900 in Sudan near N'Goureyma, 20 miles north of two different sides. (Cohen, 190la.) 902 N'Goureyma
COLLECTIONS 4 x 2 and 2 x I em in size, penetrated the thin shield near Heidelberg (about 4 kg, blunt endpiece), Washington the trailing edge (Cohen 1901 a; 1903d). Cohen concluded (I ,518 g), Chicago (990 g), Canbe_rra (97 5 g), Budapest from both the exterior, drop-like appearance and from the (939 g), Hamburg (882 g), London (871 g), New York interior structure that the mass had remelted or at least (85 2 g), Paris (711 g), Ti.ibingen ( 412 g), Vienna (346 g), softened throughout as it passed the atmosphere. Bedford Bally (312g), Calcutta (182g), Copenhagen (155 g), Oslo (I 938) disagreed with this conclusion, and the present (144 g), Uppsala (137 g), Bonn (134 g), Yale (87 g), Prague examination, likewise, shows that N'Goureyma only ablated (59 g), Moscow (58 g), Berlin (29 g), Strasbourg (26 g), in the way usually met within meteorites of oriented Vatican (I 6 g). The end piece with the two holes, weighing flight. 6,565 g, was offered for sale in 1921 and possibly passed into a private collection.
DESCRIPTION The 37.7 kg mass was roughly wedge-shaped and 58 em long. Its largest width of 28 em occurred at one third its length. Varying between I and 9 em in thickness, the mass was so thin as to be bounded practically by only two surfaces which met along a pretty sharp edge. One surface, extending from the blunt leading edge, was more convex than the opposite that was flat or slightly concave. The Figure 1260. N'Goureyma (University of Heidelberg). Close-up of meteorite was deeply grooved, with furrows that generally the end piece showing prominent ridges and furrows radiating from a radiated from the blunt apex; and two holes, approximately common apex. Scale bar approximately 3 em.
Figure 1261. N'Goureyma (U.S.N.M. no. 559). Almost full cross section of the thinner part of the mass. All troilite inclusions appear as more or less perfect spherules. The metal is a polycrystalline aggregate of inch-size precursor taenite grains. Deep-etched. Scale bar 2 em. S.l. neg. 1333. N'GOUREYMA - SELECTED CHEMICAL ANALYSES Cohen's analysis was performed on 8 g material which values are very high. Berkey & Fisher (I 967) analyzed the contained troilite and chromite (but not daubreelite, as meteorite for chlorine and found 1-8 ppm, which is high reported in the original analysis); therefore, his S and Cr compared to that of other falls. percentage ppm References Ni Co p c s Cr Cu Zn Ga Ge Ir Pt Cohen 190la 9.26 0.60 0.05 370 7700 1500 400 Lovering et al. 1957 0.56 80 <2
microhardness of 180±20 as opposed to the interior hardness of 215±15. The etched sections reveal three anomalous features: the polycrystallinity, the absence of Widmanstiitten struc ture, and the fine distribution of troilite. The mass is a polycrystalline aggregate of original austenite grains, 24 em across. They appear to be elongated in the long direction of the mass, but unfortunately no good sections of this type were available since most of the meteorite originally was cut by Minod in parallel, 0.3-1 em thick slices perpendicular to its long direction. In the austenite grain boundaries are numerous wedge- and foil-shaped troilite bodies, typically 2 mm long and 0.1 mm thick. No superstructure, like dendrites or a washed-out Widmanstiitten structure could Figure 1262. N'Goureyma (Copenhagen no. 1904, 1588). Detail of be found, so the assumption of any such preexisting the heat-affected zone. Fusion crust is out of focus at upper right. A structures must remain extrapolation without preserved troilite nodule is partially ablated away, but the pit is refilled with fusion crust from adjacent parts of the surface. Etched. Scale bar evidence. The poly crystalline structure as seen today may, 100 1-' · in fact, rather be the result of sintering at 1000-1 200° C, where sulfur-rich liquids promoted the densification. When the polycrystalline austenite cooled, the cooling rate must have been significantly higher than for Treysa, Bacubirito and other irons of corresponding composition that devel oped a normal Widmanstiitten structure. In N'Goureyma not a single kamacite lamella is present; the austenite is transformed to what looks like martensite at low magnifica tion but at higher magnification is seen to be a duplex ex+ r structure that may well be termed a tempered martensite. The taenite forms oriented 0.5-1 11 wide, irregular ribbons that are situated in veined kamacite. The veins divide the kamacite into 2-5 11 wide cells. Neumann bands are absent. While the cooling rate was sufficiently rapid to prevent Widmanstiitten formation it did not completely suppress heterogeneous nucleation and growth around the troilite inclusions, where in several places a 10-150 11 wide zone of Figure 1263. N'Goureyma (Copenhagen no. 1904, 1588). Several precursor taeni te grain s showing grain boundary cracks due to low swathing kamacite may be found. coherence across the troilite-rich boundaries. Also numerous troilite The matrix is best explained under the assumption that spherules in the grain interiors. Etched. Scale bar 2 mm. the austenite, under relatively rapid cooling, transformed to
The regmaglypts are 24 em in diameter on the convex side and somewhat larger and shallower on the flat side. The mass is covered with a black, matte, somewhat weathered oxidic fusion crust in which are numerous 0.1-1 mm pinpoint holes and elongated grooves from ablation-melted troilite. Already on the surface it may be readily seen that the tiny troilite bodies must be thread shaped and uniformly oriented through the whole mass, parallel to its long direction. The ablation-melted metal has spilled over the edges and locally forms 1-2 mrn thick laminated deposits on the flat rear side. Otherwise it is 100-400 11 thick. It is a rapidly solidified dendritic-cellular aggregate of austenite with a significant proportion of interdendritic sulfide eutectics. The exterior parts of the fusion crust are rich in Fe-S-0 eutectics.
The fusion crust has a microhardness of 310±30. Under Figure 1264A. N'Goureyma (Copenhagen no. 1904, 1588). The troilite forms sheets along the grain boundaries, but spherules in the the fusion crust is a 2-3 mm thick, heat-affected zone which grain interiors. Narrow, asymmetric rims of swathing kamacite are is difficult to observe optic3.lly but is characterized by its also visible. Etched. Scale bar 300 1-' · 904 N'Goureyma
a 2 and that this metastable phase - either immediately or 5-10 11 across, of chalcopyrrhotite are located at the edge later under reheating - decomposed to fine-grained, pless of some troilite grains, closely associated with fine-grained itic a+ 'Y. The experimental background for this interpreta dispersed iron. The troilite is subdivided by shear zones in tion has been given by Buchwald (1966). 50-100 J.1 passive blocks that display undulatory extinction due to plastic deformation. The shear zones themselves and The omnipresent troilite inclusions of the grain interior the interphase boundaries against the metal are recrystal are, in sections, perpendicular to the long dimension of the lized to 1-5 J.1 grains and may even be melted locally. The meteorite, circular or crescent-shaped. On sections parallel structures are probably due to shock. to the long direction of the meteorite a major part of the In the metallic matrix, thin oriented troilite platelets troilite inclusions have the form of commas and droplets, are common. They are typically 200 11long but only 1-2 J.1 always tapering against the same thin end of the mass. This thick and polycrystalline. They may represent high temper "fluidal" structure is rare in iron meteorites but may be ature cracks which became filled with troilite precipitates related to the uniformly oriented but larger troilite "belem before the cracks could be sealed by diffusion. nites" of Cape York, Chihuahua City, Santa Luzia, Santa Point counting of the macroscopically visible sulfides Rosa and Bendego. on a 9.5 cm2 section gave: The troilite contains numerous, euhedral chromite 4 troilite inclusions ;;. I mm in diameter, totaling 3.5 mm 2 crystals that range from 10 J.1 to 1 mm in size and are 75 troilite inclusions 0.3-0.9 mm in diameter, totaling 15.0 mm2 somewhat brecciated. Daubreelite is absent. A few grains, 90 troilite inclusions <: 0.2 mm in diameter, totaling 1.0 mm2 The total of 19.5 mm 2 corresponds to about 2 volume % FeS or 0.45 weight % S. Cohen's analytical result of 0.77% S was evidently from a section still richer in troilite. Schreibersite and rhabdite were not observed, in agreement with the low analytical value of 0.05% P. Cohen (1901a: 155) reported a 30 x 2 mm plate-shaped schreibers ite crystal near the fusion crust. This must, however, be a misinterpretation of some of the near-surface cracks that are partially filled with fusion crust. Since the cracks display veinlets of fused metal, they must, at the latest, have formed in the atmosphere - probably by simultaneous fissuring during the violent deceleration and ablation melting of the low-melting grain boundary troilite. The meteorite is more corroded than other observed falls. The crust is partially converted to limonite, and the Figure 12648. N'Goureyma (Copenhagen no. 1904, 1588). The troilite nodules are somewhat weathered. Limonitic vein troilite nodules have been exposed to deformation. They are lets, 1011 wide, are common near the surface, and the large, decomposed into cells with undulatory extinction, separated by intergranular cracks that locally attain a width of 1 mm and recrystallized and sometimes shock-melted material. Polished. threaten to split whole sections are also corroded. The Crossed polars. Scale bar I 00 J.!.. chlorine content, as reported by Berkey & Fisher (1967),
Figure 1265. N'Goureyma (Copenhagen no. 1904, 1588). The Figure 1266. N'Goureyma (Copenhagen no. 1904, 1588). In the duplex matrix at high magnification. Cell boundaries in kamac duplex matrix there are several lamellae similar to this one. It is ite (K). Irregular ribbons and lamellae of taenite. Etched. Scale bar apparently a troilite lamella, less than 1 J.l. thick, which entirely 30J.L. disrupts the continuity of the a+ 'Y matrix. Etched. Scale.bar 30 J.!.. N'Goureyma- Niagara 905
148 g slice (no. 2963, 16 x 6 x 0.3 em) 380 g slice (no. 2964, 17 x 8 x 0.5 em)
Niagara, North Dakota, U.S.A. Approximately 48°0'N, 97°56'W
Coarse octahedrite, Og. Bandwidth 1.4±0.2 mm. Neumann bands. HV 220±10. Judging from the structure, a group I iron related to Toluca, with about 8% Ni, 0.5% Co and 0.2% P. Perhaps a mislabeled Toluca specimen.
HISTORY According to Preston (1902a), a small mass of II5 g was found two miles southeast of Niagara, Grand Forks Figure 1267. N'Goureyma (Copenhagen no. 1904, 1588). A cubic County, in the early part of August, I879. It was chromite crystal (chipped) with two troilite blebs (T). Etched. Scale bar 300 J.l.. discovered by F. Talbot who was making a collection of rocks and minerals on his father's ranch. The meteorite was acquired by Ward's Natural Science Establishment and distributed in small fragments around I902-04 (see, e.g., Price List of I904 and Ward's catalog I904a: I9). Farring ton (19I5: 342) reviewed the literature.
COLLECTIONS Chicago (25 g), Yale (I9 g), London (I6 g), Vatican (8 g), Berlin (3 g).
ANALYSES Preston (1902a) reported 7.37% Ni, O.I3% Co , 92.67% Fe; but this analysis appears inadequate.
DESCRIPTION Figure 1268. N'Goureyma (Copenhagen no. 1904, 1588). Troil· The following paragraph is quoted from Preston ite (T) and a large, sheared chromite crystal (below). A cluster of (1902a) since he is the only one who has seen the entire small idiomorphic chromite crystals is situated in the troilite at the top. Etched. Scale bar 50 J.l.. sample: "The meteorite measured 30 x 40 x 50 mm and weighed suggests some terrestrialization, too. It appears that the 115 g. lt was very much oxidised, of a brownish-black mass was left exposed to the tropical climate for a color, and showed no trace of the original crust considerable period after its fall, and it is, in fact, doubtful whatever. In sa wing it crumbled into small fragments of from 2 to 4 or 5 grams weight each. The largest piece whether the reported fall date can be relied upon. obtained weighed 26 g. On etching two pieces composed N'Goureyma is an anomalous meteorite, structurally as of unoxidized iron, an octahedral structure was strongly well as chemically. It is, so far, the meteorite with the brought out in the Widmanstiitten figures, the kamacite lowest concentration of gallium and germanium. It has been plates being somewhat broad, with a second series of termed a brecciated or a recrystallized octahedrite, but markings of hairlike lines upon them about the size of the Neumann lines on the Braunau iron," these descriptions are misleading since no true Widmanstiit ten pattern is present; and the "breccia" comes from a The largest piece mentioned above came to the Field misinterpretation of a ustenite grain boundaries. / Museum, Chicago, and has kindly been loaned to me by N'Goureyma may be the result of aggregation plus sintering Dr. E. Olsen. The sample measures 2I x 2I x II mm and of fine-grained material, followed by a cooling that was contains some of the original oxidized surface. The etched rapid relatively to what the normal octahedrites underwent. section displays a coarse Widmanstiitten structure of The metallic part of N'Goureyma resembles in numerous straight, short (~ ~ IO) kamacite lamellae with a width of respects the metal of Tucson (Ring). I.40±0.20 mm. The kamacite is rich in subboundaries decorated with I J1 rhabdites. It also shows numerous Specimens in the U.S. National Museum in Washington: Neumann bands, some of which are visibly bent. The 895 g slice (no. 559, 25 x 6 x 0.7 em) microhardness is 220±IO, in accordance with the distorted, 95 g part slice (no. 1499, 8 x 5 x 0.5 em) cold-worked structure. 906 Niagara -N'Kandhla
Taenite and plessite cover I 0-15% by area, both as comb and net plessite and as spheroidized and martensitic Nieder Finow, Frankfurt (Oder), East Germany varieties. The '}'-spherules of the sphero-plessite are 2-20 J1 52°50'N, l3° 56'E across, while the '}'-lamellae of the pearlitic plessite are 0.5-2 J1 wide. Selective corrosion has converted the duplex A small mass of 287 g was found in 1940 near Nieder Fin ow, Kreis textures to beautiful patterns of 'Yin black "limonite." The Eberswalde, in Brandenburg. It was described as a coarse octahedrite martensitic varieties of the fields exhibit acicular high by Nebern & Schuller (1950); the entire mass is in the Humboldt University, Berlin (Wappler & Hoppe 1969: 375). A preliminary nickel, high-<:arbon zones, intercalated with retained analysis by Wasson (1972: personal communication) shows austenite. In places, the plessite shows numerous pointed 8.27% Ni , 76 ppm Ga, 271 ppm Ge, 2.6 ppm Jr. This, together with a-platelets only 1-5 J1 wide. the structure, suggests that Nieder Fin ow is a group I iron related to Schreibersite occurs as a 2 x 3 mm single crystal and as Bischtiibe and Toluca. numerous 10-80 J1 wide grain boundary precipitates. The rhabdites are 1-10 J1 across. Due to plastic deformation of Niro. See Verkhne Udinsk the metallic matrix, the brittle phosphides are sheared ; the rhabdites are, e.g., often shear-displaced their own width. The bulk phosphorus content is estimated to be N'Kandhla, Natal, South Africa 0 .20±0.05%. Cohenite occurs as an irregular 0 .2-0.5 mm wide rim 28° 46'S, 30°38'E around the large schreibersite crystal. It is fissured, and the fissures are filled with terrestrial corrosion products. De Medium octahedrite, Om. Bandwidth 0.85±0.12 mm . Decorated Neumann bands. HV 250±15. composition to ferrite plus graphite has not begun. The Group liD. 9.96% Ni, 0.64% Co, about 0.3% P, 71 ppm Ga, 83 ppm schreibersite-cohenite aggregate is enveloped by a I rom Ge, 18.5 ppm Jr. wide rim of swathing kamacite. Only a single troilite inclusion was noted on the small HISTORY section. It was a 25 J1 wide single crystal with some A mass of about 17.5 kg was observed to fall on pentlandite veining from terrestrial corrosion. August I , 1912 at approximately I :30"p.m. in the district The fragment is oxidized and penetrated by 0.1 mm of N'Kandhla near the junction of the Buffalo and Tugela Rivers. Stanley (1914), who described the meteorite and wide limonite veins. No heat-affected a 2 zone could be detected. The original surface can, however, not have been gave numerous photographs, also published the reports of far away, since a small amount of fusion crust was five eyewitnesses; from these the following information has identified. It filled a 0.1 rom wide crack which extended been extracted. Dedica, the wife of a Zulu chief, was from the surface to a depth of I mm. It was metallic and cutting grass near her kraal when she heard a loud formed an extremely fine, dendritic ( ~ I p) melt, suggest explosion. Then all the hillside was filled with a deafening ing rapid solidification by heat conduction through the cold walls of the fissure. Niagara seems to have been a fully developed sample of 115 g except for some loss by terrestrial corrosion. It is a typical coarse octahedrite closely related to Toluca and the other group I irons. In -its detailed morphology and struc ture it is, in fact, indistinguishable from the numerous small specimens collected in the Toluca strewnfield, compare page 1209. Whether it is , in fact, a mislabeled Toluca specimen is impossible to say at this late date. Another, more remote, possibility is that Niagara is a minor fragment of New Leipzig; the distance between the localities is, • however, 400 km and the structures are different in several Figure 1269. N'Kandhla (U.S.N.M. no. 2611). Violently folded details. kamacite and taenite at the surface. The heat-affected 0< 2 zone extends from the surface to A. The deformation is either preatmos pheric or due to severe disruptive forces during atmospheric flight. Nico. See Gibeon Etched. Scale bar 500 J.L.
N'KANDHLA - SELECTED CHEMICAL ANALYSES percentage ppm References Ni Co p c s Cr Cu Zn Ga Ge Ir Pt Cobb 1967 0.64 272 60 19 Wasson 1969 9.96 71.8 83.3 18 N'Kandhla 907 sound which grew louder until she heard and saw the (< 0.3 J.l) of what may be carbides. The microhardness of meteorite strike the ground five meters away. Stones flew the kamacite is 250±15. in all directions, and she threw herself on her face in a great Taenite and plessite cover about 30% by area. The fright; later, she never dared look at the meteorite, nor go taenite has brown-etching borders which stand in marked to the spot. The native catechist reported that the mass fell contrast to the martensitic-plessitic interiors. A complete almost vertically and made a 25 em deep and 60 em wide plessite field will have a 10-20 J.1 stained taenite border, hole in the sparse soil that covered the vertical schists. The followed by taenite with a few, sharp martensite needles. meteorite crushed a boulder, rebounded and rolled about Then follows a zone of dense martensite and then a five meters downhill. The grass where it came to rest was tempered martensite. The interior is an, optically, easily undamaged, so the mass could not have been very warm. resolvable duplex a+ 'Y mixture, the directions of which The sergeant of police had heard a huge explosion and clearly reflect the martensite orientation and the bulk feared a disaster at one of the Natal coal mines. The Widmanstatten structure, but on a very reduced scale. The direction of the traveling meteorite was uncertain, but it stained taenite borders have a microhardness of 360±25; in appears to have come from west or northwest; the smoke the heat-affected zone they are annealed and are as soft as trail was shifted by the prevailing winds to a spiraling 165±15. column before it disappeared after a few minutes. Schreibersite is present as 0.2-0.4 mm wide, angular bodies centrally in some of the kamacite lamellae. They are COLLECTIONS monocrystalline but brecciated. They are often associated London (17 .1 kg main mass and 196 g pieces), Wash ington (146 g), Copenhagen (30 g).
DESCRIYfiON ~~y·;~?;~\;;c £fJ41~/ ~/)~~~$;! The flattened angular mass has the approximate aver "''7.!'4 age dimensions of 20 x 18 x 12 em. It is irregularly covered u·· ... · ·· ·· ·• ·· ·•· ··· ~ 11A", ·· with regmaglypts, 2-3 em in diameter. It has several cracks; the largest runs at least 16 em along the surface, is 1-2 mm ~$~~~~;:.. fl!~'!!:l!i ~- ;e..,:r.r. -;,~· · . /, / · S:tl ;;-:•, ·,:-, . . ,.,_ , " · :/!;4!:-, r 'A-l.:- wide and extends to an unknown depth. Fusion crusts of r~~ - tJ..:1: ~.~.:~ff·_,-· .·. ; ,. ·~~~ · f._', : ..J:./"1- r:_~~t..: melted metal and melted oxides cover the whole surface ,.._· ':,.~';~/."J5- i,ft/."f. 1' l ·;' ' • '.·. !J'-:.,. 'fo. : F "·f'¥!J1F·· kiA~:~ · tt(.t· .,. :: ~!j -/·,' J. :: ; ·:- l . ·'{f:A -~ - ... . ;;;;•. . I ( '{•, - .r 1:(-r.-r;,,...l, ;.' · ,., ;:jji·~ ••!',:"; ·•. . · !II • '·1~:·· I "(f} ' .·, ' . • . •, and also penetrate several millimeters into some of the f·id •:f·" •t·r:.~:/··:,· .>,·, :; ...:- ._J/·! 1; : •,;~o.i( . ..• l:~~ ;: fissures, proving that these formed before the meteorite ~ ;,{ .._:_; .·_"' ~~·;,
Figure 1172. N'Kandhla (U.S.N.M. no. 2611). Detail of the heat affected 012 zone. The kama cite has been through an 01-> 'Y-> 01 2 transformation, but slipplanes and Neumann bands are still visible due to their heavy decoration with minute 'Y- and phosphide particles. Etched. Scale bar 40 p.. with a little troilite and daubreelite that apparently have acted as nucleating bodies for the phosphides. Schreibersite Nochtuisk, Yakutsk Autonomous SSR is further common as 20-40 J.l wide grain boundary precipi tates and as irregular 5-25 J.l blebs inside the coarser plessite 59°59'N, 117°35'E fields. Rhabdites are present as 1-2 J.l prisms in some kamacite lamellae. The bulk phosphorus content is esti Only four fragments, weighing 4 , 2, 1 an·d I gram, respectively, were found in the gold washings near Nochtuisk in 1876. Of these, a 3¥.. g mated to be 0.25-0.30%. specimen is in the British Museum and 1 gin Berlin. They appear to Although no graphite or cohenite was observed, there be fragments of a coarse octahedrite. For references, see Hey are structural indications of carbon being present. The (1966: 344). numerous submicroscopic particles that decorate the slip planes of kamacite and taenite (in the 500-700° C zone), the slight carburizing of the surface immediately under the Nocoleche, New South Wales, Australia metallic fusion crust, the hardness of taenite, the staining behavior of taenite and the morphology of martensite are 29°52'S, 144°13'E such indications. A bulk carbon content of 0.03% as found by Stanley (1914) may be sufficient to influence the Anomalous mixture of granulated and Widmanstiitten textures. structure in the indicated way. Decorated Neumann bands. HV 177±8. Troilite occurs with daubreelite as 0.2-0.5 mm blebs Anomalous. 6.42% Ni, 0.47% Co, about 0.17% P, 49 ppm Ga, 148 ppm Ge, 8.2 ppm Ir. that are usually more or less embedded in schreibersite. The troilite is shock-melted and has injected 1-2 J.l wide veinlets into the brecciated schreibersite. The daubreelite is partially HISTORY dissolved and may be found as 5-10 J.l subangular fragments A mass of 20.0 kg was reported in1895 by George dispersed through the troilite, which has a grain size of Raffel. It was lying upon the surface of stony ground at a 1-5 J.l. spot five miles southwest of Nocoleche Station, near On some near-surface specimens the kamacite lamellae Wanaaring, in Ularara County. The coordinates are given are distorted. The corresponding surface is severely de differently by various authors; those above are from Hey formed, either from impact against the boulder or from (I 966: 344). The meteorite was acquired by the Australian artificial hammering. Museum, in Sydney, where it was described with photo N'Kandhla is a medium octahedrite with a close graphs of the exterior and of etched slices by Cooksey structural relationship to Carbo, Elbogen and Puquios. As (I 897). Ward cut a few large slices from the mass and shown by Wasson (1969) these - with a few other figured one of them (Ward 1904a: plate 3), presently in meteorites - form the chemical group liD. Chicago. Hodge-Smith (1939: 16 and plate 7) gave other views of the meteorite. Schultz & Hintenberger (1967) Specimens in the U.S. National Museum in Washington: determined the amount of occluded noble gases, while 1 10 g part slice (no. 2397, 2 x 1 x 0. 7 em) Voshage (1967) by the 4 COLLECTIONS structure, but this is in irregular patches broken by lobed Sydney (13.0 kg), New York (2.0 kg), Chicago kamacite grains. The uniform orientation of the Widman (1.12 kg), London (950 g), Washington (203 g), Vienna stiitten lamellae proves, however, that Nocoleche once was (169 g), Harvard (141 g) , Copenhagen (100 g), Perth (57 g), a single austenite crystal. Vatican (46 g), Bonn (45 g), Ottawa (23 g), Calcutta (22 g), The Widmanstiitten lamellae are straight and long Stockholm (17 g), Berlin (12 g). (~ ~ 20) and range in width from 0.8 to 2.0 mm. The irregularity is mainly due to their lack of confinement by taenite and plessite. Plessite proper was only noted once, as DESCRIPTION a 0.5 x 0.5 mm field , on 20 cm2 ; and taenite is also only The mass has the maximum dimensions of 31 x 28 x present in small amounts, as 10-75 J1 wide bands that often 13 em, but because of its rugged shape with many reentrant parts, the weight is as low as 20 kg. At one end is a projecting knob, connected to the main mass by a slender neck, almost in the same style as seen on the Thule meteorite. At least two of the large, parallel slabs cut by Ward pass through a huge, hemispherical cavity, about I 0 em in diameter and 6 em deep. Similar pits are present on, e.g., Sacramento Mountains, Gibeon, Filomena and Maria Elena, and they appear to be preterrestrial and not due to corrosion. Some corrosion has, however, occurred. In places Nocoleche is covered by 0.5-3 mm thick crusts of terrestrial oxides; and, on the sections examined, the heat-affected a2 zone has been removed. On the average more than 2 mm is lost due to corrosion. The Neumann bands are selectively corroded because they are sensitized by fine phosphide precipitates. Etched sections present an anomalous structure which Figure 1275. Nocoleche (U.S.N.M. no. 1557). A narrow schreibers contains elements of New Baltimore, Arispe, Santa Rosa ite crystal along a kamacite grain boundary. A carbide was formerly asymmetrically precipitated upon the schreibersite, but cosmic and Dungannon but, on the whole, is unique. About 70% annealing decomposed it to granulated ferrite and lamellar graphite by area is covered by a medium-coarse Widmanstatten (black). Etched. Scale bar 100 J.L. Figure 1276. Nocoleche (U.S.N.M. no. 1557). Daubreelite (D) and Figure 1274. Nocoleche (U.S.N.M. no. 1557). Two kamacite grains troilite (T). The troilite is shock-melted and rapidly solidified. It with prominent Neumann bands and sheared rhabdites. Etched. displays characteristically curved cell walls. Polished. Scale bar Scale bar 100 J.L. 300 J.L. NOCOLECHE - SELECTED CHEMICAL ANALYSES percentage ppm References Ni Co P c s Cr Cu Zn Ga Ge Ir Pt Lovering et a!. 1957 6.42 0.47 101 124 43 134 Wasson 1969 6.4 49.3 148 8.2 Reed (1969) found the kamacite to have 6.4% Ni and 0.10% Pin solid solution. 910 Nocoleche- Nordheim show a martensitic-acicular interior. Its hardness is, how ( ~ 2% Ni) and graphite in situ and incorporated the rather ever, low (200± 10), corresponding to well-annealed taenite. passive taenite and schreibersite blebs which already were The low amount of r-phase may be expected at the 6.4% present in the cohenite. nickel level. In the kamacite, and sometimes inside 10-25 J1 wide The irregular kamacite grains are more or less equiaxial schreibersite bodies, there are numerous hard, rose colored and range from 1.0-25 mm in size. A considerable propor precipitates of carlsbergite. They occur as oriented plate tion of them, and perhaps all, appear to be developed as a lets, typically 40 x 1 J1 in size in the kamacite and as form of swathing kamacite around large and small inclu irregular blebs in the grain boundaries. sions of troilite. The areas with Widmanstiitten pattern are, Nocoleche has an anomalous primary structure, having on the other hand, practically free of foreign inclusion. It formed both granular and Widmanstiitten textures on appears, therefore, that the irregular mixture of Widman cooling; the granular areas appear to have formed first by stiitten and granular structure is due to nucleation effects, heterogeneous nucleation and growth around inclusions, the troilites having formed kamacite grains around them while the Widmanstiitten structure formed later in the selves some time before the nuclei-free remainder trans inclusion-poor parts by homogeneous nucleation. The formed homogeneously to an octahedral pattern. New secondary structures, as the shock-melted troilite, the Baltimore is a parallel example. decorated Neumann bands and the decomposed cohenite, appear to be due to shock and its associated relaxation The kamacite has numerous subboundaries and Neu heat. Nocoleche resembles New Baltimore and Mount mann bands. Both types are richly decorated with phos Dooling a little, but they are all somewhat different in their phides, generally smaller than 1 J1 in size. The kamacite has trace-element concentrations and are best treated as anom a hardness of 177±8. alous individuals, falling outside the groups. Schreibersite occurs as 10-50 J1 wide grain boundary precipitates and as similar sized blebs inside plessite and in Specimens in the U.S. National Museum in Washington: places where plessite was previously present. Rhabdites are l 77 g part slice (no. 1557, 6 x 3 x 1.2 em) ubiquitous as 1-10 J1 tetragonal prisms. The bulk phos· 26 g part slice (no. 2967, 4 x 2.5 x 0.4 em) phorus content is estimated to be 0.15-0.20%. Troilite is common as nodules, 5-16 mm in diameter, and as smaller blebs 0.5-2 mm across. The troilite contains Nordheim, Texas, U.S.A. 10-20% daubreelite in the form of parallel, 1-400 J1 wide 28°53'N, 97°34'30"W; 100m bars. Also, a few euhedral chromite crystals (HV 1125±50), 0.5-1 mm in size, are present locally, frequently in contact Ataxite. HV 240±20. with the daubreelite. The troilite is shock-melted and has Anomalous. 11.67% Ni, 0.51% Co, 0.04% P, 0.55 ppm Ga, 0.64 dissolved a significant part of its kamacite walling. It has ppm Ge, ll ppm Ir. solidified to 1-3 J1 fine-grained iron-sulfur eutectics. The associated minerals, daubreelite, chromite and a little HISTORY schreibersite, are brecciated and partly dispersed as 1-25 J1 A mass of 34 pounds (I 5.4 kg) was found in August fragments in the troilite. The troilite has been injected 1932 by Hugo Schlosser on his farm 5 km south of several millimeters out into the adjacent metal grain Nordheim, De Witt County. The cotton field in which it boundaries which have been opened. Since the fissures, was discovered had been cultivated for the first time during 10-100 J1 wide, became only partially filled, they were an easy prey to corrosive attack when the meteorite landed. Previously cohenite must have been common inside some of the plessite fields. The fields may be identified as 1-5 mm wide rhomboidal and triangular patches which now form a confusing network of recrystallized, serrated a-grains, taenite spherules and ribbons, and schreibersite blebs, the whole crisscrossed by feathery graphite veins. The morphology resembles, on a reduced scale, the decom position products of cohenite in, e.g., Wichita County, and also somewhat resembles the decomposed plessite carbide roses of Kokstad and Santa Rosa. The graphite forms 100400 J1 long and 5-20 J1 wide plumose structures, per haps with a crack along their midrib; and the associated recrystallized a-phase is very soft, HV 116±3, indicating a very low amount of nickel. It appears that the structures Figure 1277. Nordheim (Los Angeles). An ataxite displaying are best understood as original plessite-cohenite roses which oriented diffuse streaks. Four minute kamacite spindles are also at a late annealing decomposed to low-nickel kamacite seen. Etched. Scale bar 400 /-1. Nordheim 911 the 1932 season, so the meteorite was probably turned up Hoba and Kokomo. Corrosion further attacks along a few by the plow earlier that year. The mass was heavily 0.1 mm. wide cracks that extend up to four centimeters weathered and covered with loosely attached magnetic inwards. It is interesting to note how well the sulfides are scale, 2-4 millimeters thick, most of which came off in the preserved. A 200 11 troilite-daubreelite nodule embedded in course of handling. The remaining mass weighed 15.11 kg. the limonitized crust was not attacked at all, for example. It was acquired by the Texas Memorial Museum in Austin Contrary to common opinion, the sulfides, particularly if and was later fuHy described by Barnes (1939b) who monocrystalline, may survive the a-iron phase for a long presented an analysis and 11 photographs. Perry (1944: time and may even decompose after the -y-phase plate 20) gave two photomicrographs typical of the struc occasionally. ture. The coordinates as revised with the aid of a 1:24,000 Polished and etched sections display an ataxitic struc map are given above. ture, marked only by oriented streaks and by scattered troilite inclusions. The diffuse streaks are uniformly ori COLLECTIONS ented across the section; at least seven different directions University of Texas, Austin (main mass), Washington are visible, suggesting that they are unrelated to the normal (1 ,094 g). Widmanstiitten transformation which would, at most, DESCRIPTION account for four directions on an arbitrary section. Upon According to Barnes, the meteorite was of irregular microscopic examination the streaks are seen to be a little angular shape with the extreme dimensions of 21 x 19 x richer in a-phase than the surrounding matrix. The taenite 13 em. He found no fusion crust or regmaglypts, evidently blebs and ribbons in the streak zones are less oriented than because the corrosion had removed these features. The in the surroundings, but the streaks remain enigmatic. polished slice in the U.S. National Museum has no The matrix is a fine-grained intergrowth of kamacite heat-affected rim zone but, on the contrary, shows how and taenite produced from an homogeneous taenite matrix. corrosion progresses inwards in the way typical for old The intergrowths are oriented in a Widmanstiitten pattern ataxites. The fine-grained kamacite is selectively converted uniformly developed across the whole section, indicating to limonite to a depth of 0.5-5 mm, while the taenite that the parent material was a single taenite crystal. The survives temporarily and serves to anchor the corrosion kamacite is veined and thereby subdivided into 3-5 11 cells, products. Often the attack is rhythmically developed in while the taenite is in the shape of 1-2 11 wide, irregular shallow bowls, from 1-15 mm across and from 1-5 mm · ribbons. Islands, 5-10 11 across, are developed as micro deep. Similar features are seen in, e.g ., Cape of Good Hope, plessite with an outer 1-2 11 taenite rim and a duplex Figure 1279. Nordheim (Los Angeles). Duplex matrix with diffuse streaks. The two white streaks are richer in kamacite than the Figure 1278. Nordheim (Los Angeles). A cluster of kamacite adjacent dark matrix and contain better homogenized and spheroid- spindles in a rather dense"'+ 'Y matrix. Etched. Scale bar 50 p.. ized taenite particles. Etched. Scale bar 50 p.. NORDHEIM - SELECTED CHEMICAL ANALYSES Gonyer also reported 0.02% chlorine, which was meteorite, it is more likely that the chlorine is mainly of interpreted as lawrencite, although the mineral was not terrestrial origin, accumulated during a long exposure to actually seen. Considering the weathered state of the ground water. percentage ppm References Ni Co p I c s Cr Cu Zn Ga Ge Ir Pt Gonyer in Barnes 1939 11.69 0.51 0.04 Schaudy et al. 1972 11 .64 0.55 0.64 11 912 Nordheim - Norfolk interior, difficult to resolve optically. The microhardness of lamellae have been sheared and bent gently by plastic the matrix, averaging over numerous a+ r units, is 240±20. deformation. The troilite has a microhardness of 270±20, Alpha needles occur scattered through the matrix with the daubreelite, of about 350. a frequency of 0.8 per mm2 • They are usually 10-30 J.1 wide Kamacite has been nucleated irregularly upon the and about 10 times as long. When they are best, they are sulfide inclusions. A rim of kamacite, 30-50 J.1 wide, around seen to be oriented parallel to the Widmanstiitten directions part of the larger inclusions is very common. Only of the matrix. Some of them have been nucleated by 2-10 J.1 occasionally have a-lamellae started to grow from these daubreelite and troilite blebs which are now engulfed by rims in a Widmanstiitten pattern. Where kamacite has not the lamellae, but the majority are inclusion free. nucleated, a 2-10 J.1 thick shell of solid taenite is still in Schreibersite and rhabdite are absent in harmony with direct contact with the sulfides. the low phosphorus content. Barnes (1939b) reported Nordheim is an ataxite which structurally and chem schreibersite and presented photomicrographs of it; this is, ically is unrelated to the ataxites of group IVB. It is further however, a misinterpretation of the kamacite needles just different from Del Rio, Tucson and Monahans which have described. the same approximate nickel content; it resembles Guffey Troilite is common in all sizes, from 2 J.1 up to 3 mm. in some respects. Most of the larger inclusions are rather spherical, while the smaller may be round, bar-shaped or plate-shaped. The Specimen in the U.S. National Museum in Washington: troilite is monocrystalline and displays lenticular pointed 1 ,094 g slice (no. 3190, 13 x 9 x 3 em) twins due to plastic deformation. Daubreelite covers 5-20% of the troilite inclusions as parallel lamellae that range from Norfolk, Virginia, U.S.A. 1-100 J.1 in size. In several inclusions the daubreelite 36°54'N, 76° I8'W Medium octahedrite, Om. Bandwidth 1.00±0.15 mm. Distorted e-structure. HV 305± 15. Group IliA. 7.48% Ni, 0.49% Co, < 0.1% P, 21 ppm Ga, 38 ppm Ge, 10.5 ppm Ir. HISTORY The history of this 23 kg mass is obscure. According to Mac Naughton (I 926) and Reeds (I 937: 604), the meteor ite was observed to fall in 1906, but, as pointed out by Nininger (1937a) and others, this is out of the question. It is not known where it was found. Reeds (op.cit.) stated that it was exhibited at the Jamestown (Virginia) Exposi tion in 1907 by Dr. E.A. :Shubert of Virginia. It was again exhibited in Pittsburgh, Pennsylvania, in 1910, 1911 and 1912. By 1923 when the meteorite was acquired by the Figure 1280. Nordheim (Los Angeles). A rhomboid nodule com posed of troilite (dark) with fine daubreelite lamellae (light). A thin American Museum of National History, it had been cut into taenite rim is still in contact with the sulfides. Etched. Scale bar two pieces of 21.6 kg and I ,275 g. The smaller piece was 50 ll· exchanged with Ward's Natural Science Establishment '1 1111 111 "1"''1""1''''1' II 1111 II III 11 111 ''1' II '1 1111 1111 Figure 1281. Nordheim (U.S.N.M. no. 3190). Another troilite Figure 1282. Norfolk (Tempe no. 410.3) A 33 g part slice showing daubreelite nodule, under crossed pollars. The daubreelite is dark; the distorted and indistinct Widmanstiitten structure. A deformed the troilite, light and displays multiple twinning. Etched. Scale bar troilite- COLLECTIONS New York (20.9 kg main mass and 338 g slice), Harvard (200 g), Chicago (145 g), Washington (110 g), Los Angeles (99 g), London (90 g), Tempe (33 g). Figure 1283. Norfolk (Tempe no. 410.3). Cloudy taenite with severe kneading. Shock-hatched kamacite with three distorted DESCRIPTION carlsbergite platelets. The central one has nucleated small rhabdite The specimen in the U.S. National Museum is weath crystals. Etched. Oil immersion. Scale bar 20 IL· ered with up to 2 mm thick, limonitic crusts locally. The troilite inclusions are veined by pentlandite. The heat affected zone is, however, preserved in many places as an up to 1 mm thick rim of finely granulated o: 2 • The grain size is rather small, 20-50 11 across, as it usually is when formed from a shock-hardened E-structure. The microhard ness is 190±10. Norfolk is a medium octahedrite with undulating, long (W ~ 25) kamacite lamellae with a width of I.OO±O.I5 mm. While the parent crystal, no doubt, was a single undeformed austenite crystal the present Widmanstatten structure is severely distorted, indicating that significant plastic defor mation took place after the 'Y ~ o: transformation was completed. The kamacite is of the contrast-rich, cross hatched E-type, associated with shocks, and its microhard ness is 305±15. There is a smooth hardness gradient from .. Figure 1284. Norfolk (Tempe no. 410.3). A cloudy taenite lamella I90 in the rim zone to 305 in the interior which is met with showing violent deformation. Shock-hatched kamacite on either at a depth of 6-10 mm (hardness curve type I). side. Etched. Oil immersion. Scale bar 20 IL · NORFOLK - SELECTED CHEMICAL ANALYSES percentage ppm References Ni Co p I c s Cr Cu Zn Ga Ge Ir Pt Wiik & Mason 1965 7.5I 0.65 Cobb I967 0.49 I I63 2I II Wasson & Kimberlin I967 7.45 I 20.2 38.1 10 914 Norfolk - Norfork occur in some kamacite lamellae. The bulk phosphorus information was available when Nininger in the mid-thirties content is estimated to be about 0.08-0.09%. learned about the fall. The finder had been dead for several Troilite is rather common as 0.05-5 mm angular or years and the community seemed to have no recollection rounded bodies which usually contain about 15% daubree whatsoever of the fall. Nininger (1937a) described the lite in the form of parallel, narrow lamellae. The troilite was fragment and gave three photographs but was unable to once monocrystalline, but, as a result of the plastic locate the remaining, probably larger, mass. La Paz (1938) deformation mentioned above, it is now severely brecciated discussed the unusually deep impact hole of the small body. and shows undulatory extinction or martensitic lenticular Nininger & Nininger (1950: plate 17) gave a photograph of deformation twins. It is frequently sheared and displaced in the well-preserved exterior. Jaeger & Lipschutz (1967b) successive steps, each 50-100 f.1 wide, but it is not shock found the kamacite to be shocked between 130 and melted. Also present are small, 20-100 f.1 crystals showing 400 k bar. Fireman & Schwarzer (1957) examined the 3 He, rhythmic intergrowth of alternating 1 f.1 wide troilite and 3 H and 6 Li isotopes. Tilles & Tamers ( 1963) discussed the daubreelite lamellae. reasons for tritium being lower than expected in Norfork Chromite occurs as 100-500 f.1 euhedric crystals, some and other iron meteorites. Schaeffer & Heymann (1965) of which have served as nucleation centers for troilite and counted 3~1, 39Ar and 311Ar and found an exposure age of for a minute quantity of phosphides. The troilite may have 690-700 million years. Voshage ( 1967) estimated the decomposed later to form some daubreelite and in these exposure age to be 700±80 million years. Hintenberger cases chromite and daubreelite are found in intimate et al. (1967a) measured the concentration of the noble contact. The aggregates are usually crushed by the plastic gases. In these works it was assumed that the mass of the flow of the surrounding metal. fall was only 1 kg; it is, however, almost certain that a In the kamacite matrix are numerous hard, 20 x 1 f.l, considerably larger body fell but only 1 kg was recovered. platelets of carlsbergite. The coordinates above are those of Norfork. Norfolk is a weathered medium octahedrite which is structurally and chemically closely related to Boxhole, COLLECTIONS Hen bury, Costilla Peak and other irons of the phosphorus Tempe (481 g), London (97 g) , Washington (60 g), Los poor end of group IliA. Angeles (9 g). Specimen in the U.S. National Museum in Washington: 110 g part slice (no. 1294, 9 x 3.5 x 0.7 em) Norfork, Arkansas, U.S.A. 36°13'N,92°17'W; 150m Medium octahedrite, Om. Bandwidth 1.05±0.15 mm. Neumann bands. HV 250± 15. Group lilA. 7.92% Ni, 0.50% Co, 0.14% P, 20.4 ppm Ga, 41.2 ppm Ge, 0.3 ppm Ir. HISTORY A mass of unknown weight fell in October 1918 near Norfork, Baxter County. Isaac C. Luther allegedly saw it fall. While searching for a large mass next day, he only Figure 1285. Norfork (Tempe no. 296.1). The recovered mass shows located a fragment of 1 ,050 g which was recovered from a distinct regmaglypts and well-preserved fusion crusts. Scale bar 120 em deep hole. Unfortunately, very little detailed approximately 2 em. NORFORK - SELECTED CHEMICAL ANALYSES Berkey & Fisher (1967) mapped the chlorine distribu other falls examined, but 10 to 104 times lower than for tion of a 2 cm2 slice adjacent to the surface. The chlorine weathered finds. ranged. from 0.05 to 2 ppm, a range similar to that for the percentage ppm , References Ni Co p c s Cr Cu Zn Ga Ge Ir Pt Wasson & Kimberlin 1967 7.88 20.4 41.2 0.3 Moore et al. 1969 7.95 0.50 0.14 20 70 170