550 



Dr. Walter Flight — History of Meteorites. 



that in Stromeyer's paper, already alluded to, the specific gravity of 

 the silicate is given = 3-27 ; and he shows that, although the mineral 

 analysed by Stromeyer contained undecomposed silicate, or more 

 probably asmanite, the ratio of Fe to Mg is the same as in the above 

 analyses. 



By treating with hydrochloric acid the dark-coloured grains con- 

 stituting the second ingredient of the meteorite and forming about 

 one-third of the mass of the mixed silicates the iron staining them 

 is removed, and they are left in a state of colourless purity. This 

 mineral, to which Maskelyne has given the name asmanite, 1 is silicic 

 acid, possessing the specific gravity of quartz after fusion, and 

 crystallising in forms belonging to the orthorhombic system. The 

 grains of asmanite are very minute and much rounded, and, although 

 entirely crystalline, they very rarely present faces offering any 

 chance for a result with the goniometer; from several thousand 

 little grains comprised in some two grammes of material Maskelyne 

 obtained a very few crystals with sufficiently distinct crystallographic 

 features to be available for measurement. He found the parametral 

 ratios of asmanite to be : 









a : b 



: c - 



= 1-7437 : 1 



: 3-3120 





The angles, as calculated from 



these data and as found on 



seven 



different crystals, 



are as 



follow : 













A. 



B. 



C. 



D. E. F. 



G. 





'100,403= 21° 



33' 







21° 31' 









101= 27 



46 



27° 40' 



27°"48' 



27 46 



27° 49' 27° 25' 27° 65' 



27° 44' 





102= 46 



29 



46 18 



• •• 



46 31 



46 2 







103= 57 



40 





• ■• 



57 34 



57 25 



57 35 





001= 90 







9o" 



• •• 



90 









001,103= 32 

 203= 51 

 102= 43 



20 

 42 

 31 



32 22 

 51 32 

 43 34 





32 19 









101= 62 



14 



62 17 



■ ■• 



62 14 







/ 100,010= 90 

















1 110= 60 



10 



.,, 



60 13 



60 10 



60 10 





j "110 = 119 



50 













' 110,110 = 120 



20 



••• 



120 23 





120 10 





j 001,011= 73 

 \ 010= 90 



12 





















90 







( 101,110= 63 

 ( 110 = 116 



53 





.. 





63 54 







7 



... 







116 7 







/ 001,116= 32 



28 





t . 





32 56 







) 112= 62 



21 



• •» 



., 





62 21 







j 223= 68 



33 



... 



.. 





68 36 







I 110= 90 







... 







90 







( 548,001= 63 



52 



... 







64 







\ 100= 58 



28 



... 



,, 





58 30 







i 



101= 52 



18 



... 







51 48 







The cleavage-plane 001 has a vitreous lustre, that on the planes of 

 the forms 100 and 101, as also of the rounded surface in the zone 

 with them, is usually resinous, recalling the lustre of opal. The 



1 Asman is the Sanscrit term, corresponding to the Greek &k/j.ui/, for the thunder- 

 oolt of Indra. 



