phalen] the rocks of nugsuaks peninsula ^99 



this composite nature is plainly exhibited and may be seen in detail in 

 the accompanying illustration (plate liv, 5). Macroscopically the 

 two irons appear to be mixed promiscuously, and it is impossible to 

 say with any degree of assurance which is the older, assuming that 

 there is a difference in age. On etching, as has been remarked, the 

 structure of these metallic inclusions is beautifully developed. The 

 duality in composition is accentuated and a damascene luster becomes 

 apparent. It must not be inferred, however, that the individual 

 light and dark patches of a given bleb are quadrilateral, for they 

 may be and are of almost any shape whatever. They may best be 

 described as rudely polygonal, with stippled surfaces and sharply 

 contrasted by virtue of their light and dark shades as noted above. 

 Though former writers, Nordensjold,^ Rink,- and Steenstrup,^ 

 claim to have observed Widmanstatten figures in some irons, others 

 have been found which do not show such markings. In the speci- 

 men at hand, there is no regular orientation of surface markings, 

 the parallel elongated grooves having been produced during the 

 polishing. 



It has been remarked that two different irons are present. In the 

 absence of a separation and chemical examination, such a statement 

 needs qualification. From the physical point of view, this is true. 

 A chemical examination may, however, reveal similarity in com- 

 position — in this case, the marked difference in structure then might 

 be explained as a peculiar phase of isomerism, viewed from the 

 standpoint of the ultimate chemical molecules, and from the physical 

 side the differences presented may be assigned to peculiarities in the 

 orientation of the physical as contrasted with the chemical mole- 

 cules. The solution of this problem, however, lies beyond the scope 

 of a petrographical discussion and belongs to the sphere of the 

 metallographer. 



In thin section the basaltic portion of this rock is seen to be com- 

 posed almost entirely of pyroxene and plagioclase feldspar with 

 abundant albite twinning. Of these two components pyroxene is by 

 far the more abundant. It is perfectly colorless and stands out, in 

 virtue of its strong relief, from the accompanying weakly refracting 

 feldspar. It occurs in small irregular patches among the lath-shaped 

 feldspar microlites. Then it occurs in larger, irregular masses, 

 usually elongated and in forms approaching rectangles. When in 



^ Geol. Magazine, ix, 1872, pp. 88, 461. 



^ Oversigt over Kgl. Danske Videnskaberncs Sclskabs ForliandL, 1854, p. i. 



^ On the Presence of Nickel-iron with Widmanstatten Figures in the Basalt 

 of North Greenland, K. J. V. Steenstrup, 1882, Meddelclscr om Gronland, 

 IV, pt. II, 1893, p. 115. 



