Los Capitancillos Hills (New Almaden Mine)
Map SatelliteThis large area, which includes the famed New Almaden Mine, contains several plant communities but consists primarily of grasslands, chaparral and oak woodlands.
In addition to numerous exotics, the grasslands include such natives as Agrostis exarata, Bromus carinatus, Danthonia californica, Elymus glaucus and Hierochloe occidentalis. Much of the grassland is on shale-derived soils, but some is serpentine-derived and supports a sparser growth.
Among the chaparral species are chamise, Adenostoma fasciculatum, California sagebrush, Artemisia californica, Ceanothus spp., canyon gooseberry, Ribes menziesii, and poison oak, Toxicodendron diversilobum.
Coast live oak, Quercus agrifolia, covers approximately a quarter of the area. Valley oak, Quercus lobata, is abundant; other oaks present include blue oak, Quercus douglasii, leather oak, Quercus durata, black oak, Quercus kelloggii, and interior live oak, Quercus wislizenii. In the more mesic area, big-leaf maple, Acer macrophyllum, California bay, Umbellularia californica, sycamore, Platanus racemosa. and the willow Salix scouleriana are present.
Animals are relatively abundant and typical of the Santa Cruz Mountains. Of note is the black swallowtail, Papilio philenor, which is abundant here.
The New Almaden Mine first went into production in 1846. Known to the Indians who had used the cinnabar for decorative purposes for centuries, it has produced over a third of the entire United States mercury output.
Most of the rocks in the ore-bearing areas are of the Franciscan formation which have been intruded by sill-like bodies of serpentine. The serpentine was hydrothermally altered, particularly along its margins, to silica-carbonate rock. Cinnabar, the principal ore, was introduced along a series of fractures and replaced the silica-carbonate rock bordering these fractures, forming unusually rich ore bodies. Other minerals found here include bornite, chalcopyrite, galena, stibnite and sphalerite. The mine reached a point 747 meters (2,450 feet) below the surface, making it the deepest mercury mine in the world.
Integrity: At the New Almaden and the other mines the landscape in the immediate vicinity has been considerably altered. There are roads and recreational facilities in the area. Fumes from smelting operations denuded some of the area in the past but now most of the vegetation is in good condition.
Use: Education, light recreation
Ref: Bailey, E. H. and D. L. Everhart, 1964. Geology and Quicksilver Deposits of the New Almaden District. United States Sur. Prof. Paper 360, 206 pp.
August 1982
Inventory of California Natural Areas
Revision © 2009 Steven Louis Hartman