104 W. H. HOBBS — METEORITK FROM ALGOMA, WISCONSIN 



fibers or horns of metal being still attached to the surface (see plate 6, 

 figure 2, and plate 7, figure 2). The small V-shaped notches in the 

 marginal contour are rather striking, and perhaps indicate that there 

 was a shearing component of the stress b}^ which the metal was ruptured. 

 A very thin film of oxide quite unlike the scale upon the back covers 

 the marginal area of fracture. 



Composition and Texture 

 chemical composition of meteorite 



The chemical analysis of the Algoma iron was kindly undertaken at 

 my request by Mr Arthur A. Koch, laboratory assistant in quantitative 

 anal3^sis at the University of Wisconsin. Duplicate analyses were made 

 of samples of 5 grams each. The material used for this purpose was in 

 thin plates from the sawed cross-section. 



On dissolving in acid, evaporating to dryness, and redissolving, the 

 residue was very slight. After weighing, this residue was treated with 

 hydrofluoric acid, and no gritty substance remained. The analyses 

 yielded results as follows, the iron being in the one case determined b)^ 

 the gravimetric and in the other by the volumetric method: 



' 12 



Iron 88.60 88.64 



Nickel 10.64 10.62 



Cobalt 77 .91 



Phosphorus 14 .16 



Silica 02 .02 



Sulphur Trace Trace 



Copper None None 



Carbon None None 



100.17 100.35 



WIDMA NN.STA TTEN FIQ URES- THE TRIA D 



The Algoma meteorite is an octahedral siderite rich in kamacite and 

 taenite and relatively poor in plessite. The kamacite bands are of three 

 types : First, there are the relatively thick bands (.6 to 1 millimeter) 

 which cover the space of the section in a fairl}'^ regular network ; second, 

 there are parallel series of perfectly contiguous finer bands (.1 to .5 milli- 

 meter) or Kdmme, which completel}^ fill the large areas (Cohen's 

 Gescharrter Kamazit) (see plate 7, figures 1 and 2), and, lastly, there are 

 the swathing bands about schreibersite ( Wickelkamazit), v,'hich. are usually 

 of exceptional width and generally swollen and irregular as regards out- 

 lines (see especially plate 7, figure 3). Gradations between these varieties 



