176 



GEOLOGY AND QUICKSILVER DEPOSITS, NEW ALMADEN DISTRICT, CALIFORNIA 



to have been found by putting down a winze. At 

 any rate this favorable domal structure has remained 

 unexplored, and it can easily be tested, either by drill- 

 ing downward and eastward from the "mule barn" 

 for a short distance or by sinking a winze to the con- 

 tact and exploring laterally from the winze. Deeper 

 parts of contact 4 also should be regarded as favorable 

 places in which to explore for new ore bodies, but they 

 would not be so easily reached. 



OTHER BOOGESTIONS 



The places described are those that seem most clearly 

 deserving of further exploration, but they do not by 

 any means include all the places in the district that 

 may contain ore bodies. Some other places have been 

 mentioned in the detailed descriptions of the various 

 mines, and still others that do not lie near any mines 

 may be found to contain ore bodies. A notably large 

 proportion of the known ore bodies in the Los Capi- 

 tancillos Ridge have been found along the carbonatized 

 borders of serpentine masses in places where these 

 masses strike more nearly east-west than the regional 

 trend. If this distribution means anything, the mass 

 of silica-carbonate rocks cut by many hilos just north 

 of the northwest corner of the New Almaden mine 

 area deserves further attention. The occurrence, also, 

 of cinnabar in the relatively little-prospected east- 

 trending bodies of silica-carbonate rock north of the 

 Calero Reservoir indicates that these cannot be dis- 

 regarded in the search for new ore bodies, even though 

 none have been found in them hitherto. 



SUMMARY 



In summary, the New Almaden district, in spite of 

 its record of declining production and the present 

 abandoned appearance of its mines, is believed to offer 

 good possibilities for future production. Its ore bod- 

 ies have been exceptionally large and rich, and in 

 spite of extensive unwarranted exploration the two 

 largest mines the New Almaden and the Guadalupe 

 have yielded about 5.5 flasks of quicksilver per linear 

 foot of underground workings. As the ore bodies in 

 the district have been fairly closely controlled by geo- 

 logic structures, further exploration may be planned 

 in advance to take advantage of the knowledge of 

 these controls and thereby reduce the footage and cost 

 involved in finding additional ore bodies. On the 

 other hand, because all ore bodies cropping out at the 

 surface are believed to have been found, enterprising 

 management and considerable capital will be required 

 if the district is to be brought back to yield the pro- 

 duction that this geologic study indicates it is capable 

 of yielding. 



HISTORY OF THE NEW ALMADEN MINES 



The recorded history of the great quicksilver mines 

 on the New Almaden property extends through a 

 period of more than 100 years and encompasses the 

 transition of California from a sparsely populated 

 Mexican territory to a rich and populous State a 

 transition that profoundly affected the mines, the 

 miners, and the methods of mining and reducing ores. 

 Many of the resultant changes that influenced the de- 

 velopment of quicksilver mining in the United States 

 are emphasized, whereas others only mentioned briefly 

 will be of interest to persons specializing in different 

 fields of historical research. The geologists, for exam- 

 ple, will perhaps be most interested in the changing con- 

 cept of the ore gangue, from an early belief that it was 

 an extremely wide fissure filling to the present reali- 

 zation that it is the silicified and carbonatized border 

 of intrusive serpentine. The mining engineer will be 

 more interested in the development of methods of min- 

 ing. In the early days of the district, ore was carried 

 in leather bags by Mexicans who climbed up notched 

 poles from stopes hundreds of feet underground, 

 whereas in later times the mines had powerful hoists 

 and pumps; and such new techniques as the method? 

 of timbering large horizontal stopes were first devel- 

 oped at the New Almaden mine. The metallurgist's 

 interest will center around the development of quick- 

 silver-reduction equipment from crude retorts made 

 of gun barrels to modern Herreshoff and rotary fur- 

 naces. A lawyer will find much of interest in the fact 

 that many laws concerning ownership of land for- 

 merly held under grant from a foreign country were 

 first tested in the legal battles over the New Almaden 

 property, and he might diligently follow the cases 

 through State and district courts to the U.S. Supreme 

 Court, and to a final settlement by international arbi- 

 tration. A sociologist will perhaps be surprised to 

 learn of a mining community, half Mexican and half 

 American, wherein as early as 1870 medicine, dentistry, 

 entertainment, and educational lectures were provided 

 for all through compulsory monthly payroll deduc- 

 tions. The history of the mine contains much of in- 

 terest to a historian, especially the part relating to the 

 critical Civil War period, when the quicksilver so 

 necessary for the operation of the precious-metal 

 mines of the Mother Lode and the Comstock Lode 

 was nearly lost to the Northern States, through state- 

 wide feeling against the governmental seizure of the 

 New Almaden mine ordered by President Lincoln. 



The original discovery of the bright -red eye-catch- 

 ing cinnabar on Mine Hill probably was made long 

 before white men discovered California. According 

 to an oft-repeated legend, Indians who lived on Los 



