In the estimate of many people all very valuable mines are supposed to be of gold, but this is a mistake. While gold is king in California, copper mining is rapidly becoming of great importance. A continuous copper belt, the largest yet discovered in the world, exists under her soil, and while a comparatively small depth has been so far attained, the profit has been considerable. One of the largest quicksilver mines in the world is at New Almaden. The value of the output of the borax mines is over a million dollars a year. There were mined in California in 1907 over fifty different materials, most of them at a value of several thousand dollars a year, with some as high as a million and over. The mineral product of California outranking gold in value is petroleum, which has added greatly to the wealth of the state. Natural gas and mineral waters are also valuable commercial products. To many, the most interesting class among minerals is the gems, of which California yields a variety. The beautiful lilac stone, Kunzite, was discovered near Pala, San Diego County. This county has also some fine specimens of garnets, and beautiful tourmalines are being mined at a profit. San Bernardino County yields a superior grade of turquoise from which has been realized as much as eleven thousand dollars a year. Chrysoprase is being mined in Tulare County, also the beautiful new green gem something like clear jade, called Californite. Topaz, both blue and white, is being found, and besides these, many diamonds of good quality have been collected, principally from the gravels of the hydraulic mines. In 1907 there was discovered in the mountains of San Benito County a beautiful blue stone closely resembling sapphire, more brilliant but less durable. It was named, by professors of mineralogy in the state university, Benitite, from the place where it was discovered. Perhaps the most valuable of all the products of California is its water supply, either visible as in springs and streams, or underground as in artesian water. Of its use in irrigation, we have already spoken. In the production of electricity it is coming to be of the greatest importance, making possible the most stupendous works of modern times. Such is the undertaking of the Edison Electric Company in bringing down to Los Angeles, over many miles of the roughest country, power from the Kern River, tapping the tumultuous stream far up in the Sierras. The taking of the necessary machinery to those heights was in itself a wonderful labor. The power thus created is a blessing to a wide region. Chapter XVII From La Escuela of Spanish California to the Schools of the Twentieth Century