G. F. Hartt — Geological Survey of Brazil 



. RT. LXni. — The Geological Survey of Brazil. First Preliminary 

 Report made to the Counsellor Thomaz Jose Goelho de Almeida^ 

 Minister and Secretary of State fm- Agriculture, etc.; by Ch. 

 Fred. Hartt, Chief of the Geological Commission of the 

 Empire of Brazil. Rio de Janeiro. 1876.* 



On the first of May, last year [1875] I had the honor of be- 

 ing appointed chief of the Commission charged with the under- 

 taking of a geological survey of the Empire. At the same 

 time Dr. Elias Pacheco Jordao was chosen assistant, and 

 Messrs. Orville A. Derby and Richard Rathbun were appointed 

 assistant geologists. The government having given me author- 

 ity, I engaged, as the photographer of the Commission, Senhor 

 Marc Ferrez, photographer of the Royal Navy- 

 While awaiting instructions, and with the permission of his 

 Excellency the Minister of Agriculture, I went with Commander 

 E. P. Wilson to the district of Sao GouQalo, in the southwestern 

 part of the province of Minas Geraes, for the purpose of in- 

 specting the auriferous tract pertaining to a grant in which the 

 latter was interested. I examined with care the region between 

 Bella Vista, on the Don Pedro II railroad and Sao G;on9alo, 

 including the gold mines of that locality and in the vicinity of 

 the city of Campanha, verifying the occurrence of gold in three 

 distinct deposits. 



First, it is found in gneiss of what appears to be the upper 

 part of the Archaean series (Laurentian), the metal being dis- 

 tributed in more or less irregular veins, apparently conformmg 

 in direction with the stratification of the rocks. Throughout 



very much decomposed, 

 however, in situ, the decomposition at times extending to a 

 depth of 30 meters or more. While in the solid gangue the 

 proportion of gold is not great enough to pay the cost of work- 

 ing, it has been extracted with profit in many places from the 

 decomposed portion of these same lodes. It is quite probable 

 that this softened rock contains proportionally more gold than 

 the solid gneiss, owing to the accumulation of the contained 

 ♦Translated and arranged for publication in this Journal by Theo. B. Comstock, 

 Ass't Professor, in charge of Geological Department, Cornell University, Ithaca, 

 N. Y. This document has not yet been published in Brazil. A copy of the orig- 

 inal manuscript in the Portuguese language ^— ^"■~ 1--—1I" f-.-r-vahftd to ine 

 translator, with fi " '■' .... 



1 full liberty of action. The report has been shortened I 

 i little concerning the details of the Survey, i ' " ' "" *""" 





ciseness is gained without the sacrifice of perspicuity. Statements 

 opinion wiU be found to correspond as closely as possible with the i 

 author. Explanatory words within brackets are added by the translal 

 enclosed in parentheses occur thus in the original.— [t. b. c] 



