Studies for Students 



THE STRUCTURE OF METEORITES. II. 



(Continued from page 66) 

 CHONDRITIC STRUCTURE 



This characterizes the great majority of stony meteorites, 

 and being peculiar to meteorites will be described in detail. Of 

 the 314 stone meteorites listed byWillfing in his recent classifi- 

 cation, 288 are more or less largely composed of chondri. 

 Some meteorites are composed of chondri almost exclusively 

 (Borkut) while others contain them imbedded in a ground- 

 mass. The latter may be tuffaceous, glassy or crystalline. 

 The term chondrus, plural chondri, is from the Greek ^oVS/jo?, 

 a grain, the term being applied in reference to the size and 

 shape of the body. Some writers prefer the diminutive form 

 of the word, viz.: chondrules. In size chondri may vary from 

 that of a walnut to a dust-like minuteness. The larger number 

 are about the size of millet seeds. The form of chondri is 

 generally spheroidal, but varies from essentially spherical to 

 mere irregular fragments. Some chondri are flattened or oval 

 and others show apparent deformation subsequent to their 

 origin. In the latter, depressions or projections occur which 

 often look as if a hard chondrus had pressed against another 

 soft one during the process of formation. The deformed 

 chondri pass by every gradation into those which appear to 

 be rock fragments with rounded angles. The surface of the 

 chondrus is rarely smooth, being usually rough or knobbed. 

 From many friable meteorites individual chondri can easily be 

 isolated, but if the meteorite is at all coherent the chondri break 

 with the rest of the mass. The color of chondri is usually white 

 or gray, but some are brown to black. As they are often of the 

 same ingredients as the groundmass in which they are imbedded 



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