■FUNDAMENTAL PROBLEMS OF GEOLOGY. 20I 



part of their material, the amorphous nature of another part, and 

 the crystalline nature of still a third and larger part, the variations 

 in the coarseness of the crystallization, the extraordinarily large 

 crystals of the nickel-iron, the inclusion of non-metallic crystals and 

 nodules in the nickel-iron crystals, the scattered condition of iron 

 crystals among silicate crystals in many cases (sporadosiderites), 

 the presence of peculiar spheroidal aggregations (chondri), the 

 fragmental nature of these in many instances, the absence of water 

 and hydrates, the absence of free oxygen, the large proportions of 

 the nickel-iron and the magnesia, the absence of a group of minerals 

 common in terrestrial igneous rocks, viz, quartz, orthoclase, the 

 acid plagioclases, the micas, the amphiboles, leucite, and nephelite, 

 the presence of certain unstable chlorides, sulphides, and phosphides 

 unknown in the earth, and the presence of volatile and combustible 

 hydrocarbons.* 



These make up a remarkable group of characters, whose origin 

 can spring only from an equally peculiar combination of conditions. 



While the fragmental condition of many meteorites on reaching 

 the earth is due to fracturing in their passage through the air, there 

 are indications in many cases that they already had a fragmental 

 form when they entered the atmosphere. This implies that they are 

 portions of larger bodies, and that they were not aggregated, as such, 

 in free space. At least this appears true in the case of most of those 

 more massive ones that reach the surface of the earth. This of itself 

 does not exclude the view that meteorological aggregates may take 

 place in free space, and that these may have entered into the make-up 

 of the larger body from which the meteorites were derived. It, 

 however, bears on the question whether meteorites, as a rule, were 

 organized as such by the gathering together of gaseous matter or 

 .scattered particles in open space. 



Less equivocal evidence may be found in the fragmental structure 

 of many of the stony meteorites. Among the broken elements are 

 fragments of chondri. As the chondri are aggregations peculiar to 

 meteorites, their fragmentation implies disruption and reassemblage 

 in the parent body, or at least in an antecedent condition. Interest 

 and point are added by the occurrence of larger chondri inclosing 

 fragments of smaller ones. A very singular case of breccia is 

 presented by the Mount Joy meteorite, which is an aggregate of iron 



* An excellent sketch of the characteristics of meteorites is given by Dr. O. C. 

 Farrington, Jour. CtCoL, VoL IV, 1901, pp. 51, 174, 392. 



