294 Field Columbian Museum — Geology, Vol. I. 



zonal growths with chromite which also occurs alone, widely distributed 

 in the stone. The little grains of the latter mineral appear brown, 

 translucent. Also pyrrhotite (inagnctkies) is present in considerable 

 quantity and generally in large individuals. The structure of the 

 whole stone indicates a cooling from a fused liquid, a view also sup- 

 ported by the porphyritic crystals of chrysolite and the skeletons of 

 bronzite in the colorless base. There is no trace of breccia structure 

 and the occurrence of few well-defined chondri gives no further proof. 

 As has been often observed in meteorites, the whole stone has much 

 more the character of a suddenly cooled mass, a character which is 

 also indicated by the undulatory extinction of the chrysolite, the 

 skeleton growths of pyroxene and the sudden variations in composi- 

 tion. The Long Island meteorite in mineralogical characters belongs 

 to the harzburgites. If among terrestrial rocks we look for masses 

 which in a structural and mineralogical way can be compared to the 

 Long Island meteorite, it will be found that the number is a. very 

 limited one for the reason that rocks of similar composition have suf- 

 fered in most cases much decomposition, by which their structure 

 becomes indeterminable. But at all events it seems probable from 

 the few observations on, for example, the terrestrial basalts of Green- 

 land, that similar structures as they are here observed and in many 

 other meteorites are formations characteristic of cooled rocks in which 

 silicate of magnesia plays an important part, and that no grounds are 

 given for the belief that formations of this kind in any of the terres- 

 trial rocks have originated in any different way." 



To the observations of Weinschenk there is little of importance 

 to be added. The crystalline structure is perhaps hardly as promi- 

 nent megascopically as one would judge from Weinschenk's account, 

 while the chondritic structure is easily recognized in all the sections I 

 have examined. There are numerous polysomatic porphyritic chry- 

 solite chondri and typical fibrous ones of enstatite. One of the latter 

 observed was 2.5 mm. in diameter and it is evidently not cut through 

 its center. A black, seemingly carbonaceous matter, borders its outer 

 edge. The fibers are minute and lie in parallel groups extending in 

 various directions. A porphyritic chrysolite chondrus seen had a 

 diameter of 1.25 mm., a single grain reaching the size of .025 mm. 

 Another monosomatic chrysolite chondrus seen was made up of chrys- 

 olite porphyritically developed in glass and with a distinct circular 

 border of chrysolite all extinguishing simultaneously. This chondrus 

 also contained a large grain of troilite. The crystal outlines of the 

 chrysolite individuals whether developed in the chondri or out are 

 often well defined, the predominant habit being short stout crystals 



