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 dock An ore dock is a large structure used for loading ore (typically from railway cars or ore jennies) onto ships, which then carry the ore to steelworks or to transshipment points. Most known ore docks were constructed near iron mines on the upper Great Lakes and served the lower Great Lakes. Ore docks still in existence are typically about wide, high, and vary from to in length. They are commonly constructed from wood, steel, reinforced concrete, or combinations of these materials. They are commonly used for loading bulk ore carriers with high mass, low-value ore, such as iron