498 MEMOIRS NATIONAL ACADEMY OF SCIENCES, VOL. XIII. 



The iron now forms a part of the Kunz collection in the American Museum of Natural 

 History. 



BIBLIOGRAPHY. 



1. 1898: Barbour. Pub. Nebraska Acad. Sci. in Proc. Nebraska State Hist. Soc, 2d ser., vol. 2, p. 275. 



2. 1903: Barbour. Reports Nebraska Geol. Survey, vol. 1, p. 182. (Cuts of meteorite and etching figures.) 



Yorktown. See Tomhannock Creek. 



ZACATECAS. 



Mexico. 



Latitude 22° 47' N., longitude 102° 32' W. 



Iron. Zacatecas group of brecciated octahedrites (Obz) of Brezina; Caillite (type 18) of Meunier. 

 First mentioned in 1792. 

 Weight, 780 kgs. (1,716 lbs.). 



This meteorite seems to have been first mentioned in the Gazetas de Mexico ' in 1792, as 

 follows : 



From time immemorial there has been in the old St. Domingo Street of the city of Zacatecas a stone, half buried 

 in the ground, -which has been called iron stone by reason of its solidity. As to its origin there is only an oral tradition 

 that it was found by one of the first colonists when working the Quebradilla mine and has been lying near the door 

 of his house ever since. It was noticed there by Sonneschmid, recognized by him as native iron, and recommended 

 to the attention of the Government. Don Fermin Apecechea had it taken to his house and weighed; the weight was 

 ound to be 2,000 pounds. The mass is somewhat more than 1.5 yards long, not so much in breadth, and somewhat 

 over a quarter of a yard in thickness. 



The mention by Sonneschmid 2 the present compiler has not been able to consult. 

 Humboldt 3 merely quotes Sonneschmid's information, as does also Chladni. 4 

 Burkart 5 saw the Zacatecas meteorite in 1825 and described it as follows: 



This iron is 4.5 feet in length, 1 foot 9 inches wide, and of an average thickness of 9 inches. The specific gravity 

 is 7.5 and the entire mass considerably heavier than it was estimated by Sonneschmid, who fixed its weight at 2,000 

 pounds. Its form is quite irregular, although without prominent angles or sharp edges. The exterior is tolerably 

 smooth, but it has considerable pittings and is marked by many cracks and crevices. The iron of the mass is malle- 

 able, ductile, and consequently only slightly disruptable. It seems to contain many isolated particles; at all events 

 the polished surface shows rounded and jagged specks, which form a streak of a metallic luster, shading to yellow. 

 The fracture is granular and jagged; several veins are noticeable in a few places. The color of the metal is pale steel 

 gray, approximating silver white on the one hand, and, on the other, dark steel gray. Etching produces only weak 

 and irregular Widmannstatten figures. 



Partsch 6 described a section in the Vienna collection as follows: 



Compact native iron with a quite unusual quantity of pyrrhotite (and also some pyrites) distributed through the 

 whole mass, chiefly in round or lens-shaped nodules. The large polished piece in the possession of Reichenbach, 

 brought by Burkart to Europe, shows the sulphide so distributed in the iron that it forms an incomplete network. 

 The above suggestion that the sulphide may be of twofold origin comes from the fact that two colors and two specific 

 gravities may be distinguished. The iron shows zigzag clefts and on well-polished surfaces furrowed lines are visible 

 which run in different directions. No true Widmannstatten figures formed on etching, but the already mentioned lines 

 are straight and commonly lie near together. The rectangular fields between paths of lines are filled with points and 

 fine strias. These are seldom parallel but run in various directions and often radially. This is on the whole a highly 

 characteristic and remarkable iron and is difficult to describe. 



In 1849 Bergemann 7 made a study of some borings of Zacatecas, brought to him by Burk- 

 art, as follows: 



Although the meteoric iron from Zacatecas has been already repeatedly described, an analysis of the same is still 

 wanting. At the request of Dr. Burkart I therefore undertook to make such an analysis, the more willingly because 

 I had obtained through his kindness a sufficient quantity of the borings produced in the cutting of several large pieces 

 of the iron in Zacatecas. 



Specks of a yellowish-gray color, measuring one-half to one line in diameter, occur in this iron, which appear to 

 consist of magnetic pyrites. Five or six of them may be counted upon a section surface 1.5 to 2 inches in size. Accord- 

 ing to Partsch, however, the specimens of the Vienna collection and especially a large piece of the famous Reichen- 

 bach collection contain, besides magnetic pyrites, possibly also pyrites, both scattered through the meteoric iron like 

 a network, and this interspersed sulphur compound is regarded as the reason why the Widmannstatten figures can 



