14 AMERICAN MUSEUM GUIDE LEAFLETS 
, 
Essential Constituents. 
The iron of meteorites is always alloyed with from 6 to 20 per cent of 
nickel. This “ nickel-iron,” as it is commonly called, is usually crystal- 
line in texture, and when it is cut, polished and “etched” a beautiful 
network of lines is brought out, indicating plates which lie in positions 
determined by the crystalline character of the mass. ‘This network of 
lines constitutes what are called the Widmanstiitten figures, from the 
name of their discoverer. When these figures are strongly developed, 
the meteoritic origin of the iron cannot be questioned, but their absence 
does not necessarily disprove such an origin. Native iron of terrestrial 
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WIDMANSTATTEN LINES, OR FIGURES. 
Carleton Iron Meteorite. Natural size. In this iron the plates are very thin. 
origin is extremely rare and has been found almost exclusively at Disco 
Island and immediate vicinity on the west coast of Greenland. ‘The 
Disco, or Ovifak, iron contains less nickel than meteoritic iron, while 
other terrestrial nickel-irons (7. e. awaruite and josephinite) contain 
much more. Small quantities of metallic cobalt are also alloyed with 
the nickel and a little copper is sometimes found in the same association. 
Next to nickel-iron the mineral olivine, or chrysolite, is the most 
important constituent. This is a silicate of magnesium, always con- 
