New Almaden hydrothermal deposition of cinnabar from deep within the earth is found in a gangue of silica-carbonate rock formed locally by hydrothermal alteration of serpentine. The Guadalupe mine produced about 10% as much mercury as the New Almaden. There are several smaller mines in the mining district, but their ore production was not significant. The only significant quicksilver ore is cinnabar; other sulfides are present in small quantities. Mining, other than a single placer deposit of cinnabar, was underground. There is a high probability of undiscovered high-grade ore which could be found and exploited using modern techniques. Mining operations resulted in
Ore dock ore, in raw or taconite form. Ore docks are typically long, high structures, with a railway track or tracks along the top and a number of "pockets" into which ore is unloaded from railcars, typically by gravity. Each pocket has a chute that can be lowered to discharge the ore into the hold of a ship berthed alongside. The use of pockets and chutes allows the dock itself to be loaded with ore before it is transferred into the freighter. The docks' storage bins or pockets typically are wider at the top than the bottom, and they lead to movable