Mining activity in the area, including the apocryphal Governor's mine, probably began around that time, and continued until the Pueblo Revolt of 1680. The use of forced labor in gold mining is often cited as the cause of the revolt, but records of that time are incomplete, and the locations of these mines are lost. Candidates for Lost Spanish Gold Mines are frequently proposed in the Sangre de Cristo, San Juan, and Ortiz Mountains; few have been verified.