320 MEMOIRS NATIONAL ACADEMY OF SCIENCES, VOL. XIII. 



This agrees fairly well with the composition of the mass as determined by the measurement of the areas of its 

 constituents, the mean of some 300 measurements giving the following values: 



Olivine 61. 75 



Nickel iron 36. 52 



Schreibersite 1. 35 



Troilite 38 



Some 400 grams in all of the mass were taken for separation and analysis, and in the several portions of this the 

 following were separated : 



The nickel-iron alloy. — This constituent approximates one-third of the whole. It occurs in cohering spongiform 

 masses of irregular shapes, some of them measuring a centimeter along their greatest diameters, while others are merely 

 hairlike filaments. 



Etching shows that the mass of the iron constituent is made up of a darker colored alloy in which is seen fine 

 lines of a tin- white color, which are in part oriented and in part penetrate the mass in zigzag shapes. Bounding this 

 eutectic is seen a band of bright, white iron, which varies in width from a line to a millimeter. 



Examined under the glass the mass of the iron constituent appears to be made up of minute octahedrons arranged 

 in fine lamella?, and considered as a unit may be defined as a granular octahedrite containing more or less numerous 

 troilite and schreibersite areas. 



Two portions of this constituent, each weighing 10 grams, were taken for analysis, and after treating with dilute 

 acid for the separation of schreibersite, tsenite, etc., were examined as follows: In one the silicon, iron, aluminum, 

 copper, cobalt, nickel, and sulphur were determined; in the other the carbon and phosphorus, with the following 



results: 



Iron 82. 520 



Nickel 14. 044 



Cobalt 0.949 



Copper 0. 104 



Sulphur 0. 288 



Silica 0. 808 



Aluminum 0. 410 



Carbon 0. 465 



Phosphorus 0. 390 



Chlorine trace 



99. 978 



Tsenite occurs in very thin, brittle, tin-white lamellae, with a specific gravity of 7 at 20.1° C, and having the fol- 

 lowing composition : • 



Iron 63. 99 



Nickel 35. 98 



Cobalt 0. 10 



Copper trace 



Phosphorus 0.04 



100. 11 

 The material was strongly magnetic, but did not possess polarity. 



Schreibersite occurs fairly abundantly, approximating as it does 1.35 per cent of the mass by measurement and 1.95 

 per cent by analysis. It is found bounding the olivine areas and occasionally penetrating or contained in them. 

 The more common occurrence is, however, as blebs, veins, or filaments in the nickel-iron constituent. The mineral 

 has a brilliant tin-white color, is strongly magnetic, possessing polarity, and in one instance was undoubtedly crys- 

 tallized, but, unfortunately, the specimen was so brittle that it fell to pieces on attempting to measure it. 



An analysis gave the following : 



Iron 64. 990 



Nickel 18. 905 



Cobalt 0. 105 



Phosphorus 15. 700 



Copper trace 



99. 700 



Troilite occurs commonly associated with the black specular material lining the cavities containing the olivine 

 in the nickel-iron constituent. It varies in its dimensions from a coating a line in thickness to masses 2 or more milli- 

 meters thick by 10 mm. in length. Grains and flakes of troilite are occasionally contained in masses of the nickel- 

 iron alloy and may then be associated with schreibersite areas. Further, it may occur as isolated grains or flakes and 

 filling cracks in the olivine areas. 



