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THE CUERNAVACA METEORITE

In Castillo's catalogue of Mexican Meteorites (1889) he mentions, p. 3, "Meteorite of Cuernavaca, State of Morelos. It is a fragment of meteoric iron found, so it is said, on the road from Mexico (city) to Cuernavaca. It is in the National Museum of Mexico.''

While in that capitol in April of the present year, and visiting the museum, I was shown by the keeper of the mineral collections, Professor Manuel Villada, the specimen which lay in a lower compartment of one of their table cases. I promptly availed myself of permission to photograph it, and later on I was able to obtain, through the kind services of Professor Villada, permission from the Director of the Museum to cut the mass in twain and to carry away the smaller half.

The mass, as shown in the accompanying- plate, (Fig. 1, plate VII) was entire, never having had further than a minute chisel-clipping, the common way of Mexican prospectors, who test all troven metal masses in their search for silver. The length of the mass was 480 mm. (about 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 constrictions; and one of its extremities, much enlarged, projecting several inches forward of the main line of the mass in a sort of sub-cylindrical turban. The surface of the mass, though very uneven, with alternate elevations and depressions 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 is impressedĚ over the entire mass with indentations from 1/2 to 1 1/2 inches long, like chisel-marks. The section of the iron (Fig. 2, plate VII)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 schreibersite. Etching brings out well marked Widmanstätten figures of the octohedral type. In these the kamacite blades vary much in both breadth and length, causing a coarser or finer pattern in different parts of the section. The plessite patches are seen to be generally composed of alternate layers of kamacite and taenite. The latter, although in fine films between the kamacite blades, show prominently from their brightness. The characters of the etched surface of this iron show much similiarity to those of the Bella Roca siderite.

The analysis of the iron as made by Professor J. E. Whitfield, of Philadelphia, gives:

Iron, - - - - -- - 88,982
Nickel, - - - - - 10,300
The specific gravity is 7,725.

This Cuernavaca mass seems to have lain perdu since its finding, never having been described or analyzed. It has been claimed by Brezina and others as belonging to the group of Toluca irons. No one who has seen the mass in either its external or its internal features could make this mistake. Moreover, as Fletcher has shown (Mexican Meteorites, 1890, p. 79) Cuernavaca is far away, to the southeast, from the Toluca or Xiquipuco district. The two irons are as diverse in structure as they are distant in their localities.

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