METEORITES OF NORTH AMERICA. 93 



CAMBRIA. 



Near Lockport, Niagara County, New York. 



Here also Lockport. 



Latitude 43° 13' N., longitude 78° 50' W. 



Iron. Fine octahedrite (Of) of Brezina; Lockportite (type 16) of Meunier. 



Found 1818; described 1845. 



Weight, 16Jkgs. (36 lbs.). 



The history and characters of this meteorite have been fully summarized by Cohen, 13 whose 

 account is as follows: 



According to Silliman, 1 this iron was found in cultivating a field. It was of irregular elongated shape, 46 cm. 

 (18 inches) long and 14 cm. (5.5 inches) broad. It was covered by an unusually thick rust-crust and showed numerous 

 depressions on the surface which had been produced by weathering out of troilite nodules. This was known by the 

 remains of the troilite in the bottom of the pits. Numerous nodules of troilite found in the interior consisted at the 

 center of pyrrhotite easily attacked by dilute nitric acid. Toward the periphery a yellow, not decomposable troilite 

 was found. Both were surrounded by a line of white amorphous metallic iron. 



Olmsted 1 gave two analyses: 



Cu CI As Insol. 



trace =100.57 



trace trace 1.40 = 99.69 



Specific gravity=7.5257. 



Later Silliman and Hunt 2 made a new analysis of the nickel-iron and of the insoluble residue. They found it 

 consisted of magnetic dark gray foliae mingled with light flakes. Shepard 3 regarded cobalt as being present, while 

 Olmsted, Silliman, and Hunt expressly stated that cobalt was absent. Reichenbach 4 thought that Cambria and 

 Schwetz were similar on account of the s imil arity of their analyses which were, however, in both cases incorrect. In 

 his description of the trias of octahedrites Cambria was quoted as an example of metallic sheen, swathing kamacite, 

 and combs. Further, he stated that the fields appear brighter in the interior than at the edge, and at times show in 

 the neighborhood of the center a second dark zone. Thus Cambria is midway between the irons with dark and light 

 plessite. Drawing an analogy from agate, he thought that the deposition of the iron took place slowly from the outside 

 toward the center. He also distinguished a bronze colored, easily soluble troilite and an insoluble brass yellow inclin- 

 ing toward browaish-gray mineral which he regarded as pyrrhotite, and mentioned graphite as an accessory constituent. 

 Rose 6 noted the fineness of the Widmannstatten figures, likewise the bordering of many rounded inclusions of troilite 

 of the size of hazelnuts with a thin brass-yellow layer. According to Meunier, 6 Cambria belonged to those octahedrites 

 which consist almost wholly of kamacite but are mixed with some plessite and a little taenite. He designated the group 

 as Lockportite. He described the troilite as intergrown with schreibersite and daubr^elite, and bordered with graphite. 

 Rammelsberg 7 made a new analysis which differed essentially from the older. He found it to have the following 

 composition: 



Fe Ni Co Cu FeS 



88.76 10.65 0.08 0.04 0.47 =100.00 



Smith 8 first showed that the light yellow mineral bordering the troilite was schreibersite. Brezina 9 described 

 Cambria as follows: "Long, much grouped and banded hatched lamellae .0.33 mm. broad; fields and combs abundant; 

 plessite dark; large troilite nodules bordered by taenite or schreibersite and these by hatched, swathing kamacite." 



Cohen 12 gives the following description of the structure : 



Some of the bands are long, others short, and in that case much grouped. The latter are sharply separated from 

 the former and are not swollen. Some of these are hatched, others are spotted, and many show in part one and in part 

 the other formation. The etched pits occur the more abundantly the more the etching lines are lacking. All the 

 bands are coarse-granular, the spotted ones more strongly so than the hatched. This appearance is due to separation, 

 since the striae cross the clefts undisturbed. At times the kamacite contains little prisms, or elongated grains, of 

 schreibersite or cohenite running parallel with the long direction of the bands *and appearing like numerous wavelike 

 projections of the bands. The lamellae are often more or less bent and not in consequence of the shock of striking the 

 earth. Apparently this is a primary property. The taenite borders are small and visible under the lens. The struc- 

 ture of the plessite is various. A part consists of little dark grains and shining flakes. The former are 0.01 to 0.02 mm. 

 in diameter and seem to consist of black grains with a lighter border. The latter reach at the most a diameter of 0.005 

 mm. Much of the plessite composed of grains in this manner is uniform through the whole field. The shining flakes 

 are likewise uniformly distributed. Frequently the plessite appears in quadratic or small, elongated fields arranged 

 like a chessboard which are now dull and now shining but not sharply bounded. Such a structure I have never 

 observed in any other meteorite. The bright fields appear on strong enlargement not uniform, but consist of predomi- 

 nant, weakly reflecting grains and again of dull dark ones. Numerous fields are composed of complete lamellae, some 

 up to 0.1 mm. in breadth and some consisting of such in one-half and in the other half, granular plessite. No combs 



