CRYSTALLIZATION OF IGNEOUS ROCKS. 
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more abundant smaller crystals; and extremely rapid cool¬ 
ing preventing all crystallization. 
The order of importance of the factors bringing about 
crystallization appears to be as follows: 
Cooling and a certain amount of 
Time, or the rate of cooling; 
Chemical composition of the magma; 
Mineralizing agents; 
Pressure , its direct effect not having as yet been recognized. 
The phenomena of the crystallization of igneous rocks in¬ 
dicate that they were fluid molten magmas previous to crys¬ 
tallization, and throw no light on the previous condition of 
these fluid magmas. / 
