ALLEGAN METEORITE AND iMART IRON 45 



Some of them, as separated mechanically from the groundmass, 

 are simply blebs of enstatite slag with cavities resembling the 

 steam cavities in terrestial rocks or in slags from smelting fur- 

 naces (PI. IV, fig. 5). In a few cases small chondrules show 

 little depressions on one side which are continued as holes into 

 the interior for a third the diameter of the spherule. PI. IV, 

 figs. 1-7, and PI. V, figs. i-6, show the forms and outlines 

 of the chondrules as seen under the microscope in thin section, 

 or isolated. It is to be noted that in the case of a fragment, 

 such as is shown in PI. V, figs. 3, 4 and 5, no other portions 

 of the same chondrule are recognizable in the slide, showing 

 that the shattering took place prior to the consolidation of the 

 stone. This same feature is emphasized by a study of the 

 chondrules as picked out by hand, many of them being but 

 fragments, with the broken surface covered by the grayish dust 

 of the groundmass, showing that the fractures are old and not 

 due to the breaking of the stone since it reached the earth. 

 Some of the larger of these, showing surface fractures antedat- 

 ing consolidation, are shown in PI. IV, figs. 2, 3, 4, 5, 6 and 7. 

 The material obtained by passing the sand from the broken 

 stone through a sieve of about 2 mm. mesh is made up in 

 very large part of chondrules in all conditions, from mere frag- 

 ments to nearly perfect spheres. 



The groundmass of the stone is a confused agglomerate of 

 olivine and enstatite particles with interspersed metallic iron, 

 iron sulphide, and chromic iron. In no case do the silicates oc- 

 cur with perfect crystallographic outlines, nearly all, both 

 olivine and enstatite, being of fragmental nature and of vary- 

 ing size, ranging from particles a millimeter in diameter down 

 to the finest dust. The iron has the usual form of blebs and 

 extremely irregularly outlined patches serving as a cement, as 

 shown in PI. V, figs. 6, 7, 8 and 9. By reflected light it 

 shows up in strong contrast with the dull brassy yellow sul- 

 phide. This last is in irregular form also, sometimes associated 

 with the iron, sometimes quite isolated. So far as observed, it 

 never occurs as rounded blebs enclosed in the iron, as some- 

 times found in large masses of meteoric iron. On the other 

 hand, the silicate minerals do thus occur. This is mentioned 



