8 PROCEEDINGS OP THE AMERICAN ACADEMY 



On examining the specimens of the Prehistoric and Pallas irons 

 in the Harvard collection, no chromite was found, though of course 

 the absence of it in those particular specimens cannot be taken as con- 

 clusive evidence of its absence in all ; but it may be safely said that it 

 would be impossible to select equally large specimens from the Kiowa 

 County iron which would be free from this mineral. 



In comparing the three pallasites, Prehistoric, Krasnojarsk, and 

 Kiowa County, we obtain the following results. 



First. All three have the dark olivine, strongly attracted by the 

 magnet, appearing near the outside of the specimen, and frequently 

 surrounding the clear green variety. 



Secondly. All have a striking border of iron surrounding the oli- 

 vine, showing a silvery sheen from the innumerable Neumann lines. 



Thirdly. All show signs of Widmanstattian figures in the ground- 

 mass of the iron. 



Fourthly. The Krasnojarsk and the Kiowa County both have a 

 large quantity of troilite between the crystals of olivine, and also 

 patches of schreiberseit between the troilite and the iron, and occa- 

 sionally included by the iron. This same character appears, but in a 

 much less degree, in the Prehistoric. 



Fifthly. The Krasnojarsk and Kiowa specimens further show a 

 much larger proportion of iron than the Prehistoric, though closely 

 resembling each other in that respect. Figure 4, Plate II., shows a 

 slab of the Prehistoric, printed directly from the iron. 



Sixthly. The Kiowa County iron shows a very striking and far 

 more perfect crystallization than any other pallasite heretofore de- 

 scribed, so that if AVidmanstiittian figures can be used at all as a means 

 of distinguisliing irons of different falls, then the Kiowa County is 

 distinct from any meteorite thus far described. 



Lastly. The Kiowa County pallasite contains large quantities of 

 chromite distributed through it, completely permeating large masses of 

 the olivine, but no chromite is to be found in the Prehistoric iron or in 

 the specimens of the Pallas meteorite in the Harvard collection. 



In the description of the Kiowa County iron already referred to, the 

 analysis and specific gravity of the olivme of the Prehistoric are com- 

 pared with those of the Kiowa County as a proof of the identity of the 

 two ; but a glance at the following table will show that the analysis 

 of the Kiowa County olivine shows a still closer resemblance to the 

 olivine from the Pallas meteorite, and also that from Mount Etna. 



