This photo from Tres Estados is interesting. 300m long workings at that kind of scale is some serious mining.
"On January 8, 2010 the author visited the large garimpeiro Tres Estados site on processo minerais application 880090 located at UTM 224184 E, 9198823 N (WGS 84). The garimpeiros have hydraulic mined the entire east-west trending, probably structurally controlled drainage bottom for a distance in excess of 300 m. It was not clear as to whether or not if the mineralization extends out into the sides of the drainage. Disturbance was significant; however the jungle appeared to be quickly rehabilitating the site. Alluvium at this location appears to be in the order of 3 m thick. Figures 4 and 6 show the exploration licence applications, geology and Tres Estados site."
Photo 5: Garimpeiro site Tres Estados on the Aripuana Project – Block 4