DISCORDANT NATURE OF OPINIONS AS TO STRUCTURE 399 



"Aus dem oben Angeflihrten geht oline weiteres hervor, das die Struktuien- 

 haltnisse samtlicher chondritischen Meteorite der dan verstandlicli werden 

 konnen, wenn die entsteliungsweise der Chonderstukturen und der krystallinen 

 mit den Tuffastrukturen vergeseilschafteten strukturen klargestellt wiirde." 



The above quotations from the writings of well known authorities are 

 sufficient to show the general trend of opinion on the subject. 



In a systematic consideration of the problem it will be well to first 

 refer briefly to structures common to the unaltered "Kugeln" (spheru- 

 litic^^) chondrites and pass thence to crystalline spherulitic forms, and 

 thence in turn to the white, gray, intermediate and holocrystalline forms, 

 closing with a discussion of the methods by which such changes as may 

 be observed have been brought about. 



Structures common to unaltered spherulitic Forms 



The spherulitic (Kugelchen) chondrites may be briefly described as 

 consisting of numerous hard and well formed chondrules in varying pro- 

 portions and conditions of fragmentation in a tuff -like ground, sometimes 

 so loosely imbedded as to break away from it, or, again, in the crystalline 

 forms, break with it. The structure as shown in the more tuffaceous 

 forms (figure 1, plate 2) is but a disorganized mass of more or less f rag- 

 mental materials in sizes from the finest dust to those sufficient for deter- 

 mination by the unaided eye. The chondritic structure is usually the 

 most striking feature, and, indeed, some of them, as the ornansites, ap- 

 pear to be little more than aggregates of these peculiar bodies in all stages 

 of fragmentation, imbedded in a fragmental base of their own debris. 

 Concerning the fragmental nature of this base I have stated my belief 

 that there can be no question, and for the present it can be passed over. 



The chondrules themselves, with particular reference to their internal 

 structure, need further notice, particularly the glassy and porphyritic 

 forms. That these chondrules and chondroidal forms were not formed 

 in the exact positions they now occupy should be, for the most part, a 

 matter of common recognition, though as to their primary origin there 

 may still be some question. It is, however, the view of the writer that 

 the presence of these bodies is itself indicative of the tuffaceous origin of 

 any stone in which they occur, whatever may now be its condition, crys- 

 talline or otherwise. This must certainly hold true where the chondrules 

 are of a granular or porphyritic nature. In some instances, it is true, 

 conditions are such as to raise a temporary doubt with the radiate or 



'2 It is to be regretted that this term has found its way into meteoric nomenclatiire, 

 as it is quite misleading. Kugelns are not spherulites and should not be confounded 

 with them. 



