^9^ SMITHSONIAN MISCELLANEOUS COLLECTIONS [vOL. 45 



. Basalt {Bearing Native Iron) 



In addition to the occurrence of basalt in sheets, conformable with 

 the bedding, the basalt of the region about Kaersut cuts the sedi- 

 ;mentaries in dikes. Much of this basalt is decomposed, that with 

 ■original vesicular structvire (Cat. No. 75,495) having its cavities 

 iilled with zeolitic material and secondary quartz. Of peculiar in- 

 terest among the basalts is the occurrence at Kaersut of the far- 

 famed iron-bearing rock. Its occurrence at this particular point, 

 so far as the writer is aware, has not been reported before, though 

 its occurrence in the immediate vicinity has been described, as at 

 Blaafjeld (Ovifak), Mellemfjord, Asuk, Arveprindsen's Eiland, 

 Niakornak, Fortune's Bay, Fiskernaes, Ekaluit, etc., where the rock 

 has been collected and of which analyses have been made.^ 



From a petrographic point of view this is by far the most inter- 

 esting of all the specimens brought from Greenland, and so far as 

 the writer is aware is the only rock of undoubted terrestrial origin 

 known which carries native iron in any considerable amount. It 

 resembles closely an aerosiderolite, stony iron, and for many years 

 was supposed to be of extraterrestrial origin.^ Its very close re- 

 semblance to certain members of the meteorite family will be noted 

 from the accompanying illustration, plate lv. The specimen (Cat. 

 No. 53,479) now in the petrographic collection of the U. S. National 

 Museum was, before cutting and polishing, roughly ellipsoidal in 

 shape, with a major axis of 17 cm. and a minor axis of 9 cm. 

 When cut, polished, and etched with nitric acid (sp. gr. 1.42, dil. 

 I :io) the variation in size and structure of the metallic blebs was 

 beautifully developed. It will be observed that the inclusions are 

 of most irregular shapes and sizes, ranging from 1.5 cm. in greatest 

 dimension down to mere points. They often surround patches of 

 the basaltic ground mass, and frequently several blebs of minute size 

 colonize and closely simulate typical graphic structure, with, how- 

 ever, the regular outlines of the inclusions lacking. It is quite prob- 

 able that such patches represent cross-sections of the ramifications 

 of a single enclosed mass. While studying the thin sections of the 

 basalt, it was observed that these metallic segregations were not at 

 all as homogeneous as they appeared after remaining on exhibition 

 for some years. It was plainly evident that at least two diflferent 

 kinds of iron are present, a black variety and a lighter variety with 

 a silvery sheen. The irons are very irregular in outline. On etching 



' Chemical Researches on the Metallic Iron from Greenland, by J. Lorenzen, 

 1882, Meddelelser om Gronland, iv, pt. 11, 1893, p. 135. 

 - Nordenskjold in Geol. Mag., ix, 1872, pp. 88, 461. 



