106 



GEOLOGY OF THE YELLOWSTONE NATIONAL PARK. 



Table 



III. — Mineral variatio 



i in the dike 



rods of Electric Peal: 



Mineral 

 groups. 



Specimeu 

 numbers. 



Phenocrysts other than feldspar. 



Pyroxene. 



Hornblende. 



Biotite. 



Quartz. 



d, 



d 3 



d< 



d s 



d 6 



d, 



d» 



d 9 



dio 



d„ 



/ 232 



I 233 



234 



235 



r 236 



I 237 



r 238 



I 239 



240 



241 



242 



243 



244 



245 



f 246 



| 247 



I 248 



249 



250 



251 



252 



253 



254 



I 256 



257 



( " 255 



258 



, 259 



260 



261 



262 



263 



264 



265 











Much 









Much 



Much 



Some 



Some 



Some 







Much 







Much 







Much 







Much 









Much 









Much 



Much 



Much 



Much 



Much 



Much 



Much 



Much 



Much 



Much 



Much 



Much 



Much 



Much 



Much 



Some 



Some 



Little 

 Little 

 Little 

 Little 



Little 



Little 



Little 



Little 



Little 



Little . . 







Little 







Little . 







Little 







Little 







Little ... 

























Much 













Much 







Much 







Much 













Much 







Much 







Much 







Much 



Much 



Much 



Much 



Much 



Much 



Much 



Much 



Little 



Much 



Much 



Much 



Much 



Much 



Much 



















The transition indicated in the table is from acidic rocks with much 

 porphyritical quartz and biotite and very little hornblende, through inter- 

 mediate rocks with much porphyritical biotite and hornblende, to basic 

 rocks with pyroxene and little or no porphyritical hornblende or biotite, 

 but which, being' more coarsely crystalline, contain some biotite as a product 

 of the final consolidation of the groundmass, which is related in its occurrence 



