The Enigma of Californian Gold

From the first days of the gold rush in California, the San Francisco newspapers evidenced interests in the true origin of the gold placing of the state, especially in the underground mines which followed the old tertiary canals. The “Mining a Scientific Press” published letters of miners and debates of authorities in the scientific community which questioned accepted theories. An article written by Dr. Landsweert (1869) is representative of the general tone of this debate. Dr. Landsweert wrote: all the world agrees with the belief that the alluvial gold is derived in one time or another of lodes; but seeing that the largest piece of gold found in the vein-stone is insignificant when it is compared with the nuggets that have at times been found in alluviums material, has been very difficult to conciliate the belief with the experience.

Dr. Landsweert described a series of experiments in which the very diluted solutions of gold chloride and carbon material used as an agent of decomposition are mixed to obtain pellicles of precipitated of gold on top of the central parts of pyrite, iron, copper, antimonies, galena, and other metal and minerals. Using limonite, the gold was deposited in the shape of a fine metal powder.

Dr. Landsweert concluded: the occurring of larger nuggets in coarse sand deposits which have been found in quartz beds, together with the fact that alluvial gold has almost universally a higher standard of fineness; it would seem to imply a different origin for both. In the same way, it was mentioned by a contemporary, a professor Bischoff, who added combustible to the fire in saying: the very traced difference between a lot of alluvial gold and the veined gold indicates that the alluvial gold had some other origin and was transferred from the veins to the alluvia by some distinct means to the denudation; and when we consider that the gold nuggets constitute almost the most heavy material known, offering only a small surface of attack if compared with other constituents of the veins, it would be strange if they are found at a great distance of any known gold mine, as almost all the large nuggets have been.

Such discussion, naturally, attracted the opposition of those who defended the theory of the denudation and the mechanical transport of gold from the rock of origin.