152 MEMOIRS NATIONAL ACADEMY OF SCIENCES, VOL. XIII. 



19 inches), while its other diameters were about 130 mm. to 150 mm. (about 5 to 6 inches), varying in different parts 

 of the mass. The form might be described as a square-sided, irregular column, with some protuberances and con- 

 strictions; and one of its extremities, much enlarged, projected several inches forward of the main line of the mass 

 in a sort of a subcylindrical turban. The surface of the mass, though very uneven with alternate elevations and depres- 

 sions short and sharp in contour, is still smooth in texture and is quite covered with a reddish-brown crust which is of 

 unusual thickness and continuity. This surface over the entire mass is impressed with indentations from 0.5 to 1.5 

 inches long, like chisel marks. The section of the iron shows these indented lines to correspond with numerous 

 straight, short seams of troilite, which cross the mass in all parts and at all angles. There are also several small troilite 

 nodules, with one of 30 mm. in diameter. These nodules are surrounded and crossed by a narrow border of schrei- 

 bersite. Etching brings out well-marked Widmannstaitten figures of the octahedral type. In these the kamacite 

 blades vary greatly both in breadth and length, causing a coarser or finer pattern in different parts of the section. 

 The plessite patches are seen to be composed of alternate layers of kamacite and tsenite. The latter, although in fine 

 films between the kamacite blades, show prominently from their brightness. Specific gravity, 7.725. 

 Analysis (Whitfield): 



Fe . . 88. 98 



Ni . . 10. 30 



99.28 







The characters of the etched surface of this iron show much similarity to those of the Bella Roca siderite. 



Cohen 5 gave a description and analysis which led him to the conclusion that Cuernavaca 

 was a distinct fall. Later 6 he described the structure more fully, as follows: 



The lamellae are rarely long, generally short, swollen and irregularly bounded, generally not grouped but at times 

 weakly so, the tsenite border broad and very sharp; the fields abundant though not equal in quantity to the bands. 

 The kamacite is darker than the plessite. It consists in part of sharply bounded, irregularly shaped grains for the 

 most part characteristically striated so as to show lines under the microscope. In the neighborhood of the natural 

 surface these seem to be more abundant and plain than in the interior of the meteorite, although usually an opposite 

 relation occurs. Most of the fields consist of fine-grained plessite which is so rich and uniformly distributed in shining 

 flakes that it, except for a fine border, appears considerably brighter than the kamacite. The grains are so grouped 

 that it appears on stronger magnification as if isolated black grains lay in a bright, shining groundmass. In a second, 

 smaller group of fields the grains extend like striae so that a nearly octahedral structure is produced though without 

 sharp separation of light and dark striae. In many fields entire lamellae or abundant combs appear until the whole 

 field is filled with the latter. The small bands are like the large ones, in part striated, in part granular. Schreibersite 

 is sparingly visible, but analysis shows that it must be quite abundant in small particles. No other accessory con- 

 stituents were observed. 



Analysis (Hildebrand): 



Fe Ni Co P S Cr Cu 



89.70 8.76 1.19 0.33 0.12 0.00 0.05 =100.15 



Mineralogical composition: 



Nickel-iron 97. 58 



Schreibersite 2. 09 



Troilite . . 0. 33 



100.00 

 Specific gravity, 7.748. 



The mass is chiefly preserved in the National Museum of Mexico. 



BIBLIOGRAPHY. 



1. 1889: CASTILLO. Catalogue, p. 3. 



2. 1890: FLETCHER. Mexican Meteorites. Mineral. Mag., vol. 9, p. 168. 



3. 1895: BREZINA. Wiener Sammlung, p. 274. 



4. 1902: WARD. Proc. Rochester Acad. Sci., vol. 4, pp. 81, 82. 



5. 1902: COHEN. Mitth. naturwiss. Verein Neu-Vorp. u. Riigen, vol. 34, pp. 98-100. 



6. 1905: COHEN. Meteoritenkunde, Heft 3, pp. 379-381. 



Cumberland County. See Crab Orchard. 



