Br. Walter Flight — History of Meteorites. 551 



faces of the octaid forms are almost invariably rounded. The 

 optical characters confirm the measurements in showing asmanite to 

 be rhombic, the optic axes being very distinct and widely separated ; 

 their apparent angle, as measured in air, is 107° to 107° 30 / . 



The hardness of this mineral is 5-5, and the specific gravity 2*245 : 

 according to vom Eath 2-247. Of the following analyses, I. and 

 II. are the original analyses given in Maskelyne's paper, III. are 

 the results of a recent analytical examination by vom Eath : 





I. 



II. 



III. 



Silicic acid 



. ... 97-430 , 



,.. [99-210] .. 



. 96-3 



Iron oxide 



. ... 1-124 , 



..'. | 0-790 '.'. 



1.6 



Lime 



. ... 0-578 



. trace 



Magnesia 



. ... 1-509 



1-1 



100-641 100-000 99-00 



It is not a little curious to find that in his Catalogue of the Vienna 

 Collection Partseh 1 describes a specimen of the Steinbach meteorite 

 as "native iron, jagged and hackly, with quartz in grains, and a 

 yellow fluorspar." The detection by G. Eose of quartz in the oxi- 

 dised crust of the Toluca iron is the only earlier instance recorded 

 of the occurrence of free silica in a meteorite. The solvent action of 

 an aqueous solution of sodium carbonate on asmanite and quartz in 

 powder appears to be uniform. 



As regards the relation in which the three forms of crystallised 

 silicic acid stand to each other in respect to the mode of their for- 

 mation, vom Eath remarks that while crystals of quartz have in 

 most cases unquestionably separated from aqueous solution, and 

 tridymite, as a characteristic mineral of the druses of volcanic rocks, 

 appears to require the co-operation of vapour for its formation, we 

 have probably in asmanite silicic acid crystallised from a molten 

 mass which has become solid. Crystallised silica has not yet been 

 produced by fusion ; when it is, it will probably have the characters 

 of asmanite. 



The nickel-iron of this siderolite exhibits figures when etched, 

 and consists of : 





I. 



II. 



Mean. 



Equivalent Ratios. 



Iron 



... 89-975 .. 



. 90-878 .. 



90-426 



... 3229 



Nickel ... 



9-642 



8-927 ,. 



9-284 



... 0-314 



Cobalt ... 



... 0-383 .. 



0-195 



0-290 



... 0-010 



Copper ... 



trace 



trace 







100-000 100-000 100-000 



The above ratios differ but slightly from Fe : (Ni, Co) = 10 : 1. 

 Eube's examination of the Eittersgrun iron yielded very similar 

 per-centage numbers. The chromite of this siderolite gives angles 

 corresponding to a regular octahedron. 



1 P. Partseh. Die Meteoriten im k. k. Hof-Mineralien-Kabinette zu "Wien. 

 1843. Page 95. 



