Show california production IN 1915 the statistical division of the california state mining bureau under the direction of state mineralogist fletcher hamilton has after a careful inquiry made up a preliminary estimate of the mineral production of california for the year 1915 A comparison of these figures given below with those for the year 1914 shows several unusual features all with the possible exception of gold more or less attributable primarily to the disturbed commercial conditions resulting from the war in europe there is an increase of approximately in the total value the two most notable changes are the increase of zinc output from a value of 20 in 1914 to over a million and a half in 1915 and the decrease of petroleum from over to approximately bhe following is a tabulation of the estimates for 1915 gold silver copper zinc lead quicksilver other metals antimony iron molybdenum platinum tungsten vanadium petroleum natural gas structural materials cement stone etc industrial materials salines total value |