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On the structure and composition of the Chandakapur meteoric stone

Published online by Cambridge University Press:  14 March 2018

H. L. Bowman  and
H. E. Clarke
H. L. Bowman
Affiliation:
University of Oxford
H. E. Clarke
Affiliation:
Jesus College, Oxford
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Extract

Among the chief treasures of the University Museum is a large piece of the meteoric stone which fell at or near Chandakapur in the valley of Berar, India, on June 6, 1838. The specimen has been for many years in the collection, but there seems to be no record of its acquisition or previous history. The weight was formerly 3329.5 grams, but the stone was cut in two in 1899 and a portion exchanged with the late Mr. J. R. Gregory for a number of representative specimens of meteorites. A series of five thin sections were prepared at the same time, and about five grams of fragments remained, which have been used for the analysis described below.

Type
Research Article
Information
Mineralogical magazine and journal of the Mineralogical Society , Volume 15 , Issue 72 , September 1910 , pp. 350 - 376
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 1910

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References

Page 350 note 1 Owing to a clerical error this appears in Wülfing's Catalogue (‘Die Meteoriten in Sammlungen,’ 1896) as 6329 grams.

Page 350 note 2 Copies of this account, with slight differences in the weight of 1s 3 (7 lb. 7 oz. according to the Edinburgh copy) and in the spelling of names, have been found with the specimens at Oxford and Edinburgh (see below, p. 351).

Page 351 note 1 The names of the villages are variously spelled in the other copies, as Akout, Akoat ; Burgaon, Bargeon ; Burnaira, Barnaire Jacqgu (?) ; Deursulgaon, Drunlgar. ‘Ellidpoor’ should doubtless be Ellichpoor (as in the Edinburgh copy).

Page 351 note 2 If, as seems probable, No. 2 is identical with the smaller of the two specimens at Edinburgh, its weight should be 698 grams, making the total weight of the fall about 9114 grams.

Page 351 note 3 The weight given in Professor Wülfing's table (loc. cit.) for the Edinburgh specimens appears to be traceable to some error in the weighing of the larger stone or in the conversion of its weight into grams.

Page 352 note 1 Buchner, O., “Die Meteoriten in Sammlungen,” Leipzig, 1863, p. 60 Google Scholar.

Page 352 note 2 The small fragment has since been presented to the Oxford Museum, (1909).

Page 352 note 3 This fragment is said by Professor Wülfing to belong to the group Cia and not to be really Chandakapur. See, however, p. 354.

Page 353 note 1 A cast of the specimen is kept in the Museum.

Page 354 note 1 A. Brezina, ‘Die Meteoritensammlung des k.k. Hofmuseums am 1. Mai 1895.’ (Ann. des k.k. Naturhist. Hofmuseums, 1896, vol. x, p. 248.)

Page 354 note 2 Greg, R. P., Phil. Mag., 1854, ser. 4, vol. viii, p. 460 Google Scholar.

Page 355 note 1 i.e. one cut with its length parallel to the principal axis of the crystal.

Page 356 note 1 i.e. if this term be used for rhombic pyroxenes with 5 to 15 per cent. of FeO (cf. E. Cohen, ‘Meteoritenkunde,’ 1894, Part i, p. 282).

Page 356 note 2 Fouqué, F., and Michel Lévy, A., Bull. Soc. Min. de France, 1881, vol. iv, p. 280 Google Scholar ; see also E. Cohen, loc. cit., p. 300.

Page 356 note 3 Ebelmen, , Ann. Chim. Phys., 1851, set. 3, vol. xxxiii, p. 58 Google Scholar.

Page 356 note 4 Meunier, S., Compt. Rend. Acad. Sci. Paris, 1880, vol. xc, p. 349 Google Scholar.

Page 357 note 1 G. Tschermak, ‘Die mikroskopische Beschaffenheit der Meteoriten,’ (Stuttgart, 1883-1885), Plate viii, fig. 4 ; x, 2 ; xi, 2.

Page 357 note 2 G. Tschermak, loc. cit.

Page 358 note 1 Fletcher, L., Mineralogical Magazine, 1901, vol. xiii, p. 1 CrossRefGoogle Scholar ; 1894, vol. x, p. 287.

Page 359 note 1 Referred to as ‘the attracted portion’ and ‘the unattracted portion’, respectively.

Page 359 note 2 Some authors have stated that two varieties of iron sulphide occur in meteorites, of which one is magnetic and regarded as identical with terrestrial pyrrhotite (FenSn+1), while the other is non-magnetic, or only feebly magnetic, and has been assumed to consist of monosulphide (FeS). In the present paper, the name troilite is used for iron sulphide in general, without regard to its magnetic or non-magnetic character.

Page 360 note 1 Friedheim, C., Sitzungsber. Akad. Wiss. Berlin, 1888, p. 345 Google Scholar.

Page 360 note 2 L. Fletcher, loc. cit. (vol. x, pp. 288, 293).

Page 360 note 3 Tassin, V. and Merrill, G. P., Proc. United States National Museum, 1907, vol. xxxii, p. 241 Google Scholar.

Page 361 note 1 von Baumhauer, E. H., Arch. Néerland. Sci., 1871, vol. vi, p. 46.Google Scholar

Page 361 note 2 A test-experiment was made with approximately equal weights of ferrous-ammonium and nickel-ammonium sulphates ; after a threefold precipitation of the iron with ammonia as above the solution showed no trace of iron on being tested with potassium thiocyanate, while the precipitate contained no determinable amount of nickel hydroxide.

Page 362 note 1 The precipitation of nickel sulphide by means of colourless ammonium sulphide is a time-reaction, which is apparently accelerated by light. Possibly the rate of precipitation may depend upon the rate of formation of ammonium polysulphides.

Page 362 note 2 Pozzi-Escot, M. E., Compt. Rend. Acad. Sci. Paris, 1907, vol. cxlv, p. 435 Google Scholar.

Page 362 note 3 0.1667 gram of the powder was treated with 50 c.c. distilled water and evaporated to dryness on the water-bath. After repeating the process four times, the solution gave, on analysis in Jena glass vessels, 0.0008 gram CaO and 0.0017 gram Mg2P2O7.

Mr. Fletcher found the soluble material of the Zomba stone to consist principally of calcium sulphate. It is interesting therefore to note that Chandakapur contains prttctieally no soluble calcium salt, and that the aqueous extract contains no sulphate. The dissolved material consists for tile most part of sodium carbonate.

Page 364 note 1 Fletcher, L., Mineralogical Magazine, 1908, vol. xv, p. 147 CrossRefGoogle Scholar.

Page 364 note 2 The anomalous taenite, isolated by acid from the Beaconsfield iron, alone shows a higher proportion, viz. 48.6 per cent. (see Sjöström, O., Sitzungsber. Akad. Wias. Berlin, 1897, p. 1041 Google Scholar).

Page 364 note 3 Cf. Fletcher, L., Mineralogical Magazine, 1908, vol. xv, p. 147 CrossRefGoogle Scholar.

Page 365 note 1 See foot-note to § 3.

Page 365 note 2 Due to some action on the silicates during reduction. Cf. Fletcher, L., Mineralogical Magazine, 1901, vol. xiii, p. 17 Google Scholar.

Page 366 note 1 Only a portion of the material should have been used for this purpose, but by an oversight the whole was mixed with the carbonates. Fresh samples of the stone consequently had to be used for the estimations described in §§87 -20, 22, 24. The comparison given in § 21 shows, however, that the main sample resembles the smaller one of § 18 closely in composition, so that a comparison of the results obtained from the various portions is probably justifiable.

Page 366 note 2 Fletcher, L., Mineralogical Magazine, 1894, vol. x, p. 288 Google Scholar.

Page 368 note 1 In order to obtain the amount of FeO present in the silicate, an amount of Fe2O3 corresponding to the amounts of nickel-iron, phosphide, sulphide, and oxide, present in the stone (see § 22) has been subtracted from the total F2O3 preeipitated, and the remainder considered as representing FeO.

Page 368 note 2 Hillebrand, W. F., ‘The Analysis of Silicate and Carbonate Rocks.’ United States Geol. Survey Bull. No. 305, 1907, pp. 1–200 Google Scholar.

Page 369 note 1 See foot-note to § 19.

Page 369 note 2 Fletcher, L., Mineralogical Magazine, 1894, vol. x, p. 298 Google Scholar.

Page 370 note 1 See foot-note to § 3.

Page 370 note 2 Cf. Fletcher, L., Mineralogical Magazine, 1894, vol. x, p. 313 Google Scholar

Page 371 note 1 Uncorrected by blank determination.

Page 372 note 1 Cobalt was found to be present in very small amount. Manganese and zinc were shown to be absent.

Page 373 note 1 Including some, ‘glass’, which, as shown by Ulrich, mainly passes into the ‘attacked’ portion.

Page 374 note 1 Cohen, E., ‘Meteoritenkunde,’ 1894, Part i, p. 282 Google Scholar.

Page 374 note 2 Apjohn, J., Journ. Chem. Soc., 1874, ser. 2, vol. xii, p. 108 Google Scholar.

Page 374 note 3 Fe2SiO4. 2Mg2SiO4.

Page 375 note 1 Rammelsberg, C. F., Abhand. Akad. Wiss. Berlin, 1870, p. 138 ; 1879, p. 24.Google Scholar