COMPOSITION AND STRUCTURE OF METEORITES 3 



compounds resembling residue from terrestrial organic substances in 

 the meteoric stone of Cold Bokkeveld, while the French chemist 

 Berthelot thought to have extracted hydrocarbons conformable with 

 the petroleum series from the carbonaceous meteoric stone that fell 

 in Orgueil, France, in 1864.* The American chemist, J. Lawrence 

 Smith, and others since have reported repeatedly the presence of 

 carbon in both the amorphous and crystallized forms of grapliite in 

 numerous analyses of stone and iron meteorites. Amorphous carbon 

 in the form of coal black spherical masses associated with troilite is 

 a common constituent of meteoric irons, and is often surrounded by 

 a halo of schreibersite as in that of Canon Diablo, Arizona (fig. 1, 

 pi. 2). A nodule of this nature 3 centimeters in diameter was 

 analyzed by Dr. J. E. Whitfield with the following results: Carbon, 

 38.97; iron, 37.26; sulphur, 20.69; phosphorus, 0.24; recalculated this 

 gives carbon 38.97 per cent; troilite 56.89 per cent, with traces of 

 schreibersite. 



Haidinger in 1846, described a cubic form of graphite in the 

 meteoric iron of Arva (Magura), Hungary, as pseudomorphic after 

 pyrite, but which Rose suggested was pseudomorphic after diamond. 

 Fletcher in 1899 gave the name cliftonite to a cubical form of carbon 

 found by him in form of minute crystals in the meteoric iron of 

 Youndegin, Australia, and later in the irons of Cosby Creek, Smith- 

 field, and Toluca. Though at first thought to be a distinct species, 

 this, too, is now commonly regarded as pseudomorphic after the dia- 

 mond. In 1888 Jerofeieff and Latschinoff found carbon with the 

 hardness and form of the diamond in the Novo-Urei, Russia, me- 

 teoric stone. In 1889 was found the first colorless material, thought 

 from its hardness and its burning into carbon dioxide (CO2) to be 

 diamond in the Arva iron. In 1891 George A. Koenig, of Philadel- 

 phia, found a black vitreous substance, of a hardness beyond sapphire 

 and believed to be diamond, in the meteoric iron of Canon Diablo. 

 Material from this source was subsequently examined by O. W. 

 Huntington and found to contain unmistakable minute, colorless, 

 octahedral crystals of diamond.^ The French chemist Moissan 

 found in this same iron carbon in the amorphous form, as graphite 

 and as black diamond, or carbonado. Moissanite, a carbon silicide, 

 perhaps identical with artificial carborundum, was also reported by 

 this chemist in the Canon Diablo iron.^ 



Chromite and jnagnetite. — The oxides of chromium and iron, or of 

 iron alone, are common constituents of terrestrial rocks as well as of 



* Doubt as to the correctness of this and other tests for hydrocarbons in meteorites has recently been 

 expressed by P. E. Spielman. Nature, August 23, 1924. 



5 Proc. Amer. Acad., vol. 29, 1894, p. 204. 



' The fact that meteoric irons are commonly sawn by crushed carborundum raises a doubt as to the actual 

 meteoric source of this material. 



