THE ORIGIN OF THE EARTH. 



27 



The general prevalence, but partial absence, of crystallization, and 

 the kinds of crystallization imply varied thermal conditions in the 

 parent body. The amorphous condition implies the absence of fusion 

 and of the conditions of crystallization. The glassy structure equally 

 implies a molten state followed by quick cooling, while the various 

 grades of crystallization imply high temperatures variously sustained. 



Fig. 5. — Section of the Mezo-Madaras meteorite, showing a meteoritic tuff made up 

 of fragments of chondri. Portions of bronzite, chrysolite, and nickel-iron chondri 

 can be recognized. (After Tschermak.) 



The extremely large crystals (Figs. 9 and 11) suggest protracted high 

 temperature with conditions favorable for a systematic rearrangement 

 of the material. At the same time the cases in which the metallic 

 iron is scattered through the silicate material (Fig. 10) seem, at first 

 thought, to imply the absence of a thoroughly fluid state at the time 

 the segregation of the iron began, since a massing of the heavier metal- 

 lic material toward the center of gravity would naturally be expected, 

 just as in a blast-furnace metallic iron promptly separates from slag; 



