OBSERVATIONS ON THE NATURE OF THE "ORGANIZED 

 ELEMENTS" IN CARBONACEOUS CHONDRITES 



Frank W. Fitch 

 Department of Pathology, University of Chicago, Chicago, III. 



Edward Anders 



Enrico Fermi Institute for Nuclear Studies, Departments of Chemistry and Geophysical 

 Sciences, University of Chicago, Chicago, III. 



Our interest in the morphological study of carbonaceous chondrites was 

 stimulated by reports of Claus and Nagy^ and of Nagy et al.,- describing a 

 variety of "organized elements" found in Class I carbonaceous chondrites. 

 The organized elements had been classified by Claus and Nagy into 5 types on 

 the basis, primarily, of morphology. The various properties of the organized 

 elements are tabulated in table 1. Types I and II which were circular or 

 spherical were most numerous; the other types were much less abundant. A 

 total of about 1700 organized elements per milligram were reported.' ■"' 



In an attempt to confirm these observations and to characterize further the 

 composition of the organized elements, we examined samples of the carbona- 

 ceous chondrites Orgueil and Ivuna. One sample of Orgueil was obtained 

 several years ago from the Musee d'Histoire Naturelle, Paris. Another sample 

 was obtained through the courtesy of Henderson of the U.S. National Museum, 

 and was from the same fragment given to Nagy. A sample of Ivuna was ob- 

 tained through the courtesy of Roy of the Chicago Natural History Museum. 

 Conventional brightfield, phase contrast and fluorescence microscopy were 

 used. Other methods included staining with biological stains, and the use of 

 x-ray diffraction and electron microprobe analysis. 



Microscopical Observations 



Both samples of Orgueil and the single sample of Ivuna had crumbled apart 

 and consisted of fragments ranging in size from a fine dust to several millimeters 

 in diameter. Fragments were inspected visually to be certain that they were 

 free from fusion crust, paint markings, and other visible contaminants. To 

 minimize sampling errors, observations were made on the fine dust as well as 

 fragments broken from larger pieces. This dust that had accumulated at the 

 bottom of the sealed glass containers came from the surface of many individual 

 fragments and should, therefore, be fairly representative of the meteorite as a 

 whole. Because of the friable nature and the porosity of the carbonaceous 

 chondrites, it is not feasible to clean the meteorite surface. For microscopy, 

 samples of the meteorite weighing about 1 mg. were placed in a drop of glycerin 

 on a microscope slide which had been cleaned with 95 per cent ethanol. The 

 sample was gently crushed with a glass rod cleaned with ethanol. Samples 

 subjected to density separation were lightly crushed in an alcohol-cleaned agate 

 mortar. 



Initially, particles were sought which had the general morphological charac- 

 teristics of the organized elements. Because Types I and II elements were 

 circular or spherical, particles with this morphology were sought. As reported 



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