METEORIC IRON. 109 



69. METEORIC IRON. 



Iron of meteoric origin can be recognized by the 

 following peculiarities: ' 



I. Some meteoric iron contains olivine, which may 

 be detected by the eye, also gold-colored sulphuret of 

 iron. 



II. In certain kinds, especially on the oxidized sur- 

 face, yellowish, pliable laminae of a metallic lustre may 

 be observed ; they are phosphide of nickel and iron 

 (Schreibersite). 



III. Some kinds are passive, i. e., they do not reduce 

 copper from a solution of neutral sulphate of copper. 



IV. If a freshly filed, ground and polished surface 

 be immersed for five or ten minutes in dilute nitric 

 acid, peculiar, mostly crystalline delineations (Wid- 

 mannstatten's figures), or microscopic parallel lines 

 or bright points, make their appearance in most kinds, 

 thus imparting to the surface a peculiar lustre when 

 viewed in a certain direction. 



V. All meteoric iron, when dissolved in hydrochloric 

 acid, leaves a black, pulverulent residue, whilst in most 

 cases a trace of sulphuretted hydrogen is developed, 

 derived from an admixture of sulphide of iron. On 

 examining this residue (previously washed and dried) 

 under a magnifying power of from 50 to 100, in most 

 cases crystalline particles of metallic lustre, and fre- 

 quently also well-defined magnetic prisms of metallic 

 lustre, are observed, consisting of phosphide of iron, 

 phosphide of iron and nickel, and sometimes also 

 chrome-iron and graphite ; in addition to these also 

 transparent, partly colorless, partly colored grains of 

 quartz, olivine and other minerals. 



VI. Every specimen of iron of undoubted meteoric 

 origin contains as characteristic constituents, nickel, 

 cobalt and phosphide of iron and nickel. The amount 

 of nickel varies between 2 and 20 per cent. ; the cobalt 



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