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106 SMITHSONIAN CONTRIBUTIONS TO THE EARTH SCIENCES
number of the El Taco silicate inclusions in more
detail, with special emphasis on possible variations
between different inclusions.
ACKNOWLEDGMENTS.—We wish to thank Professor
Hintenberger for providing a facility for an
ingenious cutting of this large specimen of the
El Taco meteorite, Dr. H. Wanke and Dr. K.
Fredriksson for their stimulating discussions, Mr.
R. S. Clarke for selecting and providing some
samples, and Dr. B. Mason for his suggestions in
the preparation of the manuscript. One of us
(F. W.) wishes to thank the members of the Department
of Mineral Sciences of the Smithsonian
Institution for their hospitality and help during
his stay there, especially Mrs. P. R. Brenner, Mrs.
FIGURE 2.—Silicate inclusions of slice A.
C. Trice, Mr. C. Obermeyer, Mr. J. Nelen, and
Mr. A. F. Noonan. We also thank Mr. G. Moreland
for the preparation of excellent polished thin sections.
The completion of this study was made
possible through a special fund provided by the
Secretary of the Smithsonian Institution.
Macroscopic Features
Campo del Cielo is a coarse octahedrite. Figure 1
shows the Widmanstatten pattern of the etched
slice. The silicates are scattered over the whole area
of the sectioned slice. Most of them are located at
grain boundaries of the primary taenite crystals,
but several appear also in the centers of these