12 CONTENTS. 



CHAPTER VI. ROCK ALTERATION CONNECTED WITH MINERALIZATION Continued. page. 

 Alteration of the earlier andesite Continued. 



Alteration of earlier andesite, chiefly to quartz, sericite, and r.dularia Continued. 



Advanced stage of alteration 209 



Occurrence of kaolin 209 



Alteration of earlier andesite, chiefly to calcite and chlorite 210 



Transitions between alteration phases of earlier andesite 210 



Different alterations the effect of the same waters 210 



Refractoriness of potash feldspars 211 



Meaning of adularia and albite as gangue minerals 212 



Study of typical specimens 213 



Microscopic descriptions 213 



Earlier andesite from lower part of Siebert shaft 213 



Earlier andesite from Tonopah and California shaft 213 



Earlier andesite from Fraction No. 2 shaft 214 



Earlier andesite from near Mizpah Hill 214 



Earlier andesite from near Mizpah vein 214 



Typical earlier andesite from Mizpah Hill 215 



Earlier andesite from hanging wall of Mizpah vein 215 



Ore material of Mizpah vein 216 



Analyses of described types 216 



Differences of phases expressed by diagrams 217 



Study of alterations indicated by analyses 217 



Alteration of earlier andesite from lower part of Siebert shaft 217 



Alteration of earlier andesite from California and Tonopah shaft 220 



Alteration of earlier andesite from Fraction No. 2 shaft 221 



Alteration of earlier andesite from near Mizpah Hill 223 



Alteration of earlier andesite from near Mizpah vein 224 



Alteration of typical andesite from Mizpah Hill 225 



Alteration of earlier andesite from wall of Mizpah vein 225 



Alteration of earlier andesite to vein material 226 



Maximum alteration located along the vein zones 226 



Composition of mineralizing waters in the vein zones 227 



Relation of adularia to sericite as alteration products 



Formation and occurrence of adularia 228 



Conditions required for the formation of adularia 228 



Adularia as a metamorphic mineral 229 



Adularia in veins 229 



Chemistry of the alteration of soda-lime feldspar to adularia 230 



Formation and occurrence of muscovite 231 



Conditions required for the formation of muscovite 231 



Muscovite as an alteration product 231 



Distinct conditions required for muscovite and for biotite 232 



The sericitic variety of muscovite 232 



- Fluorine neoewary to the formation of mica 232 



Chemistry of the alteration of soda-lime feldspars to sericite 233 



