[JOHNSTON-ELLSWORTH] ANNAHEIM METEORITE 81 



surrounding ground mass has gone to purple or blue. It appears 

 to be quite unaffected by rust or discolouration under ordinary 

 atmospheric conditions, resembling in this respect, as well as in 

 composition the artificial alloy " Invar." The content of copper may 

 add to its rust resistant qualities since small amounts added to 

 commercial iron and steel are said to decrease corrosion. Under the 

 binocular it was found to be scratched by orthoclase and apatite and 

 not scratched by fluorite. On polished surfaces it stands in slight 

 relief.. The lamellae are flexible, but only slightly if at all elastic. 

 Sound pieces could be bent through 180° and back three or four times 

 before fracturing. Measured by a B & S gauge single blades as 

 isolated V^aried from 0.005 to 0.010 inch in thickness. They are 

 attracted and held by a common horseshoe magnet. 



The resemblance of this alloy to invar and its apparent role 

 along with schreibersite (Analysis 3) as a eutectic enveloping the 

 kamacite areas may have a bearing on the physical chemistry of the 

 meteoric irons. Invar'' is said to contain about 36% nickel and 0.5 

 per cent, each of manganese and carbon, with melting point 1425°C. 

 and density 8.0. 



Analysis 3. — Uncrystallized fractured phosphide (schreibersite?) 

 (F\. VHI, Figs. 7, 8; PI. X, Fig. 12). 



S. G.=7.2at 20.10°C. in air. 



100.52 



These results lead to no \'ery definite formula though the ratios are 

 near Fe5(Ni, Co, Cu)2P2j as may be seen below. 



MoL. Ratio-s 



1.097 1.097 



Fe ^^=0.219 ;r— -„ = 5.05 



o • 0.21/ 



lU.S. Bureau of Standards, Circular 58. 



