52 BULLETIN 149, UNITED STATES NATIONAL MUSEUM 



green-gray color, consisting of a dense ground carrying numerous 

 rounded chondrule-like bodies of a more compact texture and intern- 

 ally of a darker color, but which break away readily, often with por- 

 tions of the ground adhering. (Upper figure, pi. 30.) The ground 

 itself is so fine in texture as to render its mineralogical determination 

 by the unaided eye a matter of difficulty, though studded with small 

 whitish specks suggestive of a feldspar. The "kugels" vary in size 

 from but 2-3 mm. to rarely 20 mm. in diameter. When cut across 

 they show a darker ground than the matrix in which they are em- 

 bedded and are distinctly porphyritic even to the unaided eye. (PI. 

 30, lower figure.) In the thin section they show a normal, though 

 somewhat altered andesitic structure of feldspar and hornblende 

 phenocrysts in a microlitic ground. The kugels separate readily from 

 the matrix but are plainly not inclusions of foreign matter. Even by 

 the naked eye they may be seen on a polished surface to grade into 

 it without sharp lines of demarcation. From an examination of hand 

 specimens only, not having studied the occurrence in the field, one is 

 inclined to accept the conclusions of Szterinyi^^ to the eft'ect that they 

 are magnetic segregations liberated through the propylitic form of 

 decomposition which the stone has undergone. Whatever be their 

 origin their chondritic nature is wholly simulated. 



Messrs. Gushing and Weinschenk, in their description of the phono- 

 lites of the Hegaus,^^ mention an interesting tuff which in addition to 

 other constituents carries abundant kugel forms which are easily 

 distinguished through their dark color, hardness, and lustrous fracture. 

 These the microscope shows to be of melilite basalt, and plainly are 

 not rolled pebbles. 



Sondern kleine Answiirflinge, wie sie iiberall einen integrirenden Bestandtheil 

 der Basalttuffe bilden und durch haufig zu betrachtende centrische Structur 

 verrathen, dass ihre Form durchaus primar ist. 



In their mode of occurrence, form, and structure they are described 

 as comparable with the chondrules of meteorites. 



In response to a letter, the late Professor Gushing, then at the Gase 

 School of Applied Science in Gleveland, kindly sent one of his original 

 specimens, with permission to use as much as might be necessarj'' for 

 the investigation. This yielded the material from which the accom- 

 panying illustrations were prepared. In Figure 1 of Plate 31 a nucleal 

 augite is surrounded by a zone of elongated melilites which in a general 

 way are arrayed with their longer axes lying in the circumference of 

 a circle having the nucleus as a center. This is assumed to be the 

 "centrische" structure of the authors quoted. Be this as it may, the 

 centric structure while suggestive is not quite that of the majority 



11 Foldtani Kozlony, Budapest, Nos. 12-13, 1882-83, pp. 207-222. 

 " Tschermak's Min. u. Nat. Mitheil., vol. 13, 1892, p. 36. 



