214 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. xxvrii. 



The nickel-iroii coiistituentcomprisps about oiu'-third of the mass of 

 the entire ,sul•fa('(^ as cut, and serves as a matrix in whieh are contained 

 rounded blehs of olivine varvinj*- in size from 1 to HO millimeters in 

 diameter. Dislodoing- the olivine blebs will in u-cneral disclose a very 

 thin, black, specular film more or less com])letely lining the entire 

 cavity, and which is rich in carbon and usually contains some chlorine 

 as chloride, too-etluM- with moiv oi- less sulphur as sulphide. Next to 

 this is frecpiently found a more oi" less contiiuious layer of schi'ci- 

 bersite or troiliti', or both. Thes(> in turn are followed by the nickel- 

 iron constituent made up of kamacite, taMiite, etc. 



The olivine blebs are quite commonly penetrated by cracks in all 

 directions. These cracks may or may not bo tilled with other sub- 

 stances. In the former case they are charged either with metallic 

 iron, the black, specular chlorine-containing material above referred 

 to as commonly surrounding the olivine, and which often contains 

 chromite; with limonite (probably resulting from the oxidation of the 

 specular substance), and which also contains chromite; or, and this 

 but rarely, with schreil)ersite or troilite. 



The mass contains, approximately, the following percentage com- 

 position, calculated from the results of several analyses: 



( )liviiie 63. 15 



Nickel-iron 83. 12 



Sclireibersite 1. 95 



Troilite 69 



Chromite 1. 00 



Carbon 09 



Chlorine Trace. 



This agrees fairly w^ell with the com})osition of the mass as deter- 

 mined by the measurement of the areas of its constituents, the mean 

 of some three hundred measurements giving the following values: 



Olivine 61. 75 



Nickel-iron M.b2 



Schreibersite 1 . 35 



Troilite 38 



THt] .MINERAI.O(iICAL COMPOSITION. 



Some 4(»»» grams in all of the mass were taken for separation and 

 analysis, and in the several portions of this the following were 

 separated: 



The nu'l'el- Iron aJlo;/. — This constituent approximates one-third of 

 the whole. It occurs in coliering spongiform masses of irregular 

 shapes, some of them measuring a centimeter along their greatest 

 diameters, while others are merely hair-like filaments. 



Etching shows that the mass of the iron constituent is made up of a 

 dftrker colored alloy in which is seen tine lines of a tin-white color 

 (see figure), which are in pai't oriented and in part penetrate the mass in 



