PHYSIOGRAPHY. 



Pyroxene. 



137 



Pyroxene, if melted, and then allowed to cool slowly, crystallize and as- 

 sume an appearance little different from what they had before. 



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4. Pyroxene occurs in imbedded crystals, in various kinds of rocks, in 

 basalt, lava, &c. ; also in beds in older rocks, both in crystals and in com- 

 pound massive varieties ; it enters into the regular mixture or composi- 

 tion of several rocks, as the pyroxene rocks, some varieties of greenstone 

 and basalt ; it is likewise found in veins, traversing primitive rocks. Fo- 

 12* 



