It appears that the bottom of the pit is in the mixed oxide-sulfide zone, and that’s also what the two haul trucks in the foreground are saindak copper gold project pdf. The gray rocks visible in the pit are almost all in the primary-sulfide ore zone. Because of their large volume, porphyry orebodies can be economic from copper concentrations as low as 0.
In some mines, those metals are the main product. The first mining of low-grade copper porphyry deposits from large open pits coincided roughly with the introduction of steam shovels, the construction of railroads, and a surge in market demand near the start of the 20th century. Some mines exploit porphyry deposits that contain sufficient gold or molybdenum, but little or no copper. Porphyry copper deposits are currently the largest source of copper ore. Porphyry copper deposits represent an important resource and the dominant source of copper that is mined today to satisfy global demand.
1 to 6 kilometres with vertical thicknesses on average of 2 kilometres. 574 known deposits that are at the surface. It is estimated that the Earth’s porphyry copper deposits contain approximately 1. Porphyry deposits are formed in arc-related settings and are associated with subduction zone magmas.
There also appears to be discrete time periods in which porphyry deposit formation appears to be concentrated or preferred. Most large-scale porphyry deposits have an age of less than 20 million years. 438 million year old Cadia-Ridgeway deposit in New South Wales. It may be however, that the skewed distribution towards most deposits being less than 20 million years is at least partially an artifact of exploration methodology and model assumptions, as large examples are known in areas which were previously left only partially or under-explored partly due to their perceived older host rock ages, but which were then later found to contain large, world class examples of much older porphyry copper deposits.