4-0 SMITHSONIAN INSTITUTION 



From Queretaro, I proceeded to Mexico City, and further field 

 studies were deferred until another season. During the two and one- 

 half months spent in active field-work a considerable amount of geo- 

 logical material was collected including systematic series illustrating 

 the mineral occurrence, processes in ore formation, such as oxidation 

 and enrichment, and large exhibition specimens of lead, silver, zinc and 

 copper ores. A small collection of Indian remains and artifacts was 

 obtained at Charcas. 



