MEMOIR ON METEORITES. 275 



The composition of the nickeliferous iron corresponds to five 

 atoms of iron and one of nickel: iron, 5 atoms, 82.59; nickel, 

 1 atom, 17.41 = 100.00. 



2. Protosulphuret of Iron. — This variety of sulphuret of iron 

 found with meteorites is usually designated as magnetic pyrites, 

 leaving it to be inferred that its composition is the same as the 

 terrestrial variety. Without alluding to the doubt among some 

 mineralogists as to the true composition of the terrestrial mag- 

 netic pyrites, I have only to say that most careful examination 

 of the sulphuret detached from the meteorite in question proves 

 it to be a protosulphuret — a conclusion to which Eammelsberg 

 had already come with reference to the pyrites of the Seelasgen 

 iron, which latter pyrites I have also examined, confirming the 

 results of Eammelsberg. 



This pyrites incrusts some portion of the iron, and in places 

 is mixed with a little schreibersite. It presents no distinct 

 crystalline structure, has a gray metallic luster, and a specific 

 gravity of 4.75. The Seelasgen pyrites gave me for specific 

 gravity 4.681. The specimen of pyrites in question gave, on 

 analysis: iron, 62.38; sulphur, 35.67; nickel, 0.32; copper, trace; 

 silica, 0.56; lime, 0.08=98.91. The formula Fe S requires sul- 

 phur 36.36, iron 63.64. The magnetic property of this mineral 

 is far inferior to that possessed by schreibersite. 



3. Schreibersite. — It is found disseminated in small particles 

 through the mass of the iron, and is made evident by the action 

 of hydrochloric acid; it is also found in flakes of little size, 

 inserted as it were into the iron ; and owing to the fact that in 

 many parts where it occurs chloride of iron also exists, this last 

 has caused the iron to rust in crevices, and on opening these 

 schreibersite was detached mechanically. This mineral as it 

 exists in the meteorite in question so closely resembles mag- 

 netic pyrites that it can readily be mistaken for this latter 

 substance, and I feel confident in asserting that a great deal 

 of the so-called magnetic pyrites associated with various masses 

 of meteoric iron will upon examination be found not to contain 

 a trace of sulphur, and will, on the contrary, prove to be schrei- 

 bersite, that can be easily recognized by the characters to be 

 fully detailed a little farther on. 



Its color is yellow or yellowish -white, sometimes with a 

 greenish tinge; luster metallic; hardness 6; specific gravity 



