METEORITES — HENDERSON AND PERRY 251 



mechanically brought together; hence, the various components of 

 such stones are associated purely by chance. Thin sections of chon- 

 dritic meteorites show some complete chondrules, but usually there 

 are a great number of fragments of chondrules present. The frag- 

 mental nature of this class of meteorites is a conspicuous feature. 

 Foshag® stated: "The agglomeratic nature of chondritic meteorites 

 leaves little doubt that they are volcanic tuffs." Since in many stones 

 the iron occurs enclosing chondrules or penetrating the minute 

 fractures of silicate minerals it is logical to assume that it was 

 deposited after the fragmental silicate material was partially con- 

 solidated. With such good and abundant evidence suggesting that 

 the silicate materials were mechanically brought together, and that 

 iron was introduced after the silicates had formed, it is impossible 

 to understand why any relationship should exist between the com- 

 position of the iron and its abundance in a meteorite. 



A few studies have been made upon the etch patterns of the iron in 

 stony meteorites, and these studies indicate that all the features found 

 in the iron of iron meteorites are also present in the iron of stony 

 meteorites. There is no question but that some of the metallic in- 

 clusions in these stones are exceptionally rich in nickel — above the 

 range found in the iron meteorites — hence it is to be expected that a few 

 unusual etch patterns may be found. 



CONCLUSION 



The purpose of this discussion has been to show that some progress 

 is being made in relating the various phenomena observed in the study 

 of meteorites, although some of the most conspicuous features are still 

 but imperfectly understood. The description of stony meteorites is 

 very difficult, and often a published account is so general that it is im- 

 possible properly to classify the specimen or to correlate it with other 

 meteorites. The study of meteorites is only just beginning, and the 

 system of classification is still in the formative stage. It is unfor- 

 tunate that the interest of many persons in these objects is merely that 

 of the collector in possessing something extremely rare, when so many 

 interesting problems await the attention of ambitious students. 



• Amer. Mineral., vol. 26, p. 137, 1941. 



