i!i RANOROI i i (HRARY 



CONTENTS. 



Page. 



3tter of transmittal 5 



Introduction 7 



Production 8 



Mining and metallurgy 9 



Topography 11 



General geology , 11 



First geological survey of the district 11 



Modifications of earlier results 12 



Economic geology 14 



Earlier work 14 



Extent of productive territory 14 



Underground development 15 



Brief review of the mines 15 



Character of the ores 20 



Structural characteristics of the deposits 22 



Types of deposits 22 



Depth of oxidized zone 26 



Relations of ore bodies to depth 26 



Underground water -_ 31 



Subterranean gases 32 



Future of the district 33 



Index . . 35 



