ILLUSTRATIONS 



Plate I. Geological Map of Ruby Hill 



l*age. 



115 



174 

 II. Geological Cross-sections 



III. Minerals in section 



398 



IV. Quartz grains in section 



Y. Feldspars lu section 



402 

 VI. Micropegmatite and andesite 



404 

 VII. Andesite and basalt 



VIII. Rhvolite *^ 



56 



Fig. 1. Silurian ciuartzite west of Castle Mountain 



6') 



2. Section across Lone Mountain 



3. Nevada limestone, Jlodoc Section 



901 



4. Section across Pinon Uange 



093 



5. Granite pori>liyry dikes " 



6. Vertical Cross-section — Phcenix mine 



351 



7. Carlsbad twinn of labradorite 



8 Dia.'rain exhibiting extinction angles of a Carlsbad twin of labradorite 351 



353 

 9. Carlsbad twia of plagioclase 



VII 



