METEORITES OF NORTH AMERICA. 163 



Etching on polished surface produces distinct Widmannstatten figures like those of the Xiquipilco iron. 



In view of the above-given characteristics, the commission referred the iron to the holosiderites of Daubree. 



The commission furthermore cited the result of different experiments with the meteorite of Descubridora, of 

 which the following data may find place here. 



The piece of the meteorite used for the experiment showed especially a prismatic or cubic form which was also 

 indicated by the fracture. 



The resistance of the iron to crushing was 38 kg. (upon a cross section of 1 sq. mm.) ; resistance to tension 40 kg., etc., 



Much of Burkart's account seems to have been drawn from Barcena's u description. 

 Barcena 13 later summarized this before the Philadelphia Academy as follows: 



In the State of San Luis Potosi two aerolites of large dimensions were found. One of them, called "Meteorite de la 

 Descubridora," was sent 4 years ago to the Mexican Society of Geography and Statistics of the City of Mexico by Messrs. 

 Cabrera and Yrizar of the city of San Luis Potosi. This mass, which weighed 576 kg., was divided in several pieces 

 for the purpose of making some investigations as to its structure. The form of the meteorite was also prismatic; it 

 resembled that of a pyramid with a triangular base; the drawing taken with a photographic apparatus presented in its 

 outline several well-determined lines which formed triangular and quadrilateral figures very similar to those produced 

 by hydrochloric acid upon the polished surface of the same mass. The color of the aerolite is grayish white and its 

 texture notably crystalline. Ite specific weight is 7.38. It is composed of: 



Fe Ni Co S Cr Loss 



89.51 8.05 1.94 0.45 trace 0.05 =100 



The resistance of the iron to rupture by compression is 38 kg. to the square millimeter; the resistance to the rupture 

 by extension is 40 kg., being the section of the metallic thread of a square millimeter. The coefficient of linear dilata- 

 tion between 0" and 100 is 0.0000701. 



The analysis of the meteorite in question was made by the Mexican chemist Don Patricio Murphy. The other 

 studies were made by a commission of which I had the honor of being a member. 



The 92-pound mass was first described by Kunz " as follows: 



The Catorze mass, weighing 92 pounds, was found by a miner near Catorze, San Luis Potori, Mexico, in 1885. It 

 measures 31.5 by 34.5 by 20 cm. It shows beautiful raised octahedral markings. On one side an opening 9 cm. long 

 has been made and a piece of a chisel of native copper left in it. This piece, which is partially covered with oxide of 

 copper, is 22 mm. long on one side, 33 mm. on the other, and 14 mm. wide. 



This iron is one of the Cailite group of Stanislaus Meunier and shows the Widmannstatten lines very finely. It 

 resembles the irons of Augusta County, Virginia, of Glorieta Mountain, and others of this group. No troilite was 

 observed, the mass having been cut very little and schreibersite is only sparingly present. 



Analysis by J. B. Mackintosh: 



Fe Ni and Co P Insoluble in HNO 3 



90.09 9.07 0.24 0.60 =100 



Specific gravity, 7.509. 



This iron Kunz regarded "from all appearances" as a "new and distinct fall." 

 Castillo 21 mentions only the 576 kg. mass and describes a peculiar mineral which he found 

 in it. 



Fletcher's B views have already been referred to. 

 Meunier ** makes the following observations: 



The figures produced by this iron are identical with those of the Schwetz iron. The kamacite is composed of bands 

 more than a millimeter in size and the sides of the plessite, which are often square, are on an average 4 mm. in size. 

 The latter show under the glass very small specks of schreibersite. The kamacite is often bordered by a very fine 

 lamina of tanite. The pyrrhotine occurs in very elongated masses. 



The large mass is now in the Mexican National Museum. It is cut in two parts and the 

 parts bound with iron hoops to prevent their falling apart from the fissure already referred to 

 by Burkart as running through them. The surface of one of the masses is nicely engraved with 

 the locality, weight, etc. The 92-pound mass is preserved almost entire in the Vienna Museum. 



BIBLIOGRAPHY. 



1. 1804: DEL Rio. Tablas Mineralogicas, Mexico, 1804, p. 57. 



2. 1805: DEL Rio. Elementos de Orictognosia, Segunda parte, p. 40. 



3. 1855: SMITH. Memoir on meteorites. Amer. Journ. Sci., "d ser., vol. 19, p. 160 (Hacienda of Venagas). 



4. 1S56: BURKART. Fundorte I. Neues Jahrb., 1856, pp. 2S5-286 and 287. 



5. 1857: BURKART. Briefliche Mitteilung. Xeues Jahrb., 1857, pp. 53-54. 



6. 1858: BUBKART. Fundorte II. Neues Jahrb., 1858, p. 770. 



7. 1859: HARRIS. Dissert. Gottingen. p. 107. 



