Old Mines of Southern California / Desert-Mountain-Coastal Areas Including the Calico-Salton Sea Colorado River Districts and Southern Counties

The work surveys mining districts across southern California, combining field geology, mineral descriptions, and historical reporting. It documents individual properties and veins, details rock types, faulting, and mineral assemblages, and describes ore occurrences, gangue minerals, and processing methods including crushing, smelting, and speiss production. Assay results, mill installations, and working conditions are reported alongside practical notes on management, mismanagement, and local speculative rushes. Ground observations and underground examinations are used to interpret vein formation and displacement, while descriptions of infrastructure, assays, and experimental metallurgical procedures illustrate the technological responses to complex ores.