Nagy et al. : Environment of Orgueil Meteorite Parent Body 55 1 



The relationship shown in figure 4 may be appUcable, in general, to the 

 Orgueil meteorite parent body. From this relationship one may then speculate 

 that the Orgueil parent body had an aqueous, low temperature, slightly alkaline 

 and slightly reducing environment. It seems that sulfur was formed by some 

 unrelated process. 



The approximate positions^ of some terrestrial environments as characterized 

 by Eh and pK are shown in figure 5. It is interesting that the proposed 

 Orgueil environment resembles those terrestrial environments which are isolated 

 from the earth's atmosphere (organic rich saline waters).* 



Summary 



The Orgueil meteorite has long been known to contain bound-water, organic 

 matter, and sulfur, in addition to silicate, iron oxide, and magnesium sulfate. 

 Trace element data in Orgueil, obtained during the present study, were found 

 to be consistent with the average abundances of trace elements in chondritic 

 meteorites but they appeared dissimilar to average abundances in terrestrial 

 shales and igneous rocks. Electron microscopy showed that the meteorite 

 consists mainly of micaceous minerals. X-ray, electron diffraction studies and 

 thermogravimetric analysis confirmed the occurrence of hydrous layer lattice 

 silicates and of magnetite, in addition to some magnesium sulfate. The 

 mineral suite prescribes an aqueous environment of the parent body. The 

 parent body temperature seems to have been low to moderate and one may 

 speculate that the environment was slightly reducing and that the pH was 

 slightly alkaline. 



Acknowledgments 



A part of these studies was supported by the National Science Foundation; 

 this support is gratefully acknowledged. The authors wish to thank Vincent 

 Modzeleski of Fordham University for his able assistance in several experi- 

 ments. The authors would like to thank Brian Mason, R. F. Folinsbee, 

 Lincoln LaPaz, and E. P. Henderson for providing the meteorite samples and 

 Ralph J. Holmes for providing the mineral standards. The recent marine 

 sediment sample was received from the Lamont Geological Observatory of 

 Columbia University. The trace element analysis was performed by Ledoux 

 and Company, Teaneck, N.J.; the electron micrographs and electron diffraction 

 patterns were taken by the Ladd Research Industries, Burlington, Vt. The 

 authors would like to thank I. Fankuchen of the Polytechnic Institute of Brook- 

 lyn for his helpful suggestions regarding the x-ray diffraction analysis and for 

 permitting the use of his laboratory for making certain measurements. The 

 authors would like to thank Harold C. Urey of the University of California, 

 Brian Mason of The American Museum of Natural History, Robert M. Garrels 

 of Harvard University, I. Fankuchen of the Polytechnic Institute of Brooklyn, 



* Sagan^*" suggested that indigenous organic matter may exist buried under the surface 

 of the moon. He observed that "organisms shielded from solar illumination, perhaps in 

 congealed dust matrix interstices, might survive cosmic radiation for 10" years or more; lunar 

 subsurface temperatures are too low to impede survival." The Orgueil meteorite may repre- 

 sent the remnant of such an undergrounfl habitat, but the experimental data gathered in this 

 study do not preclude the possibilitj- that the parent body was of sufficient size to hold an 

 atmosphere and thus, bodies of water. 



