MINES 



159 



inclination of about 60 to the 1000 level. From the 

 1000 level to the 1300 level a two-compartment winze 

 extended downward at an angle of 57. The stopes 

 in the mine follow the footwall and hanging-wall con- 

 tacts of a southwest-dipping sill of serpentine, partly 

 replaced by silica-carbonate rock. The footwall stopes 

 extend downward discontinuously from the 100 level 

 to the 1000 level. The hanging-wall stopes, which lie 

 between the 260 level and the 1200 level, are even less 

 continuous. 



History and production 



Ore was first found in the Senator mine area (then 

 known as El Senator prospect) near the crest of the 

 north slope of the ridge at some time before 1863, for 

 in that year the mine was reported n to have already 

 yielded some 60 tons of good ore. In 1863 a new adit, 

 driven to a point 120 feet below the ore-bearing out- 

 crop, also reached ore, but it was abandoned without 

 further mining because of its remoteness from the 

 reduction plant in Almaden Canyon. During the next 

 46 years the prospect was mined off and on and yielded 

 a small amount of ore. Available records mention a 

 period of activity in 1872 and 1873 that resulted in 

 several hundred feet of drifting and the recovery of 

 at least 6 tons of "fine ore." 12 Further prospecting in 

 1898 and 1899 developed a little ore in about 1,000 

 feet of new workings, but the mine was abandoned 

 in 1900. 



Systematic development of the Senator mine, which 

 resulted in the recovery of more than 20,000 flasks of 

 quicksilver during the following 16 years, began in 

 October 1909, when E. J. Furst, then superintendent 

 of the New Almaden mine, turned to the Senator mine 

 in the hope of developing some ore to supply the New 

 Almaden furnaces. This hope probably was aroused 

 by a new discovery of ore at the Guadalupe mine, 

 within 600 feet of the New Almaden property. Under 

 the direction of John Drew, who remained in charge 

 of actual prospecting and mining during most of the 

 life of the Senator mine, development was started by 

 trenching the outcrops of silica-carbonate rock at the 

 top of the ridge. Low-grade ore was discovered, and 

 the sinking of the Nones shaft in the trenched area 

 was begun on December 8, 1909. By the end of the 

 following March, much of the 125 level had been 

 driven and ore had been found in its southwestern 

 part. Under the direction of two other superintend- 

 ents of the New Almaden mining property, develop- 

 ment of the Senator workings to the 400 level con- 



11 Hawley, C. D., 1864, Unpublished private report on the New Alma- 

 den mines prepared (or the Quicksilver Mining Co., November. 



12 Schuette, C. N., 1935, Unpublished private report on the New Alma- 

 den mine prepared for the Quicksilver Mining Co. 



tinued until 1912. During this period the ore, which 

 was hauled 7 miles to the Hacienda at the foot of 

 Mine Hill for furnacing, averaged 0.75 to 1.0 per- 

 cent quicksilver and is reported to have yielded about 

 3,500 flasks. In 1912 the operating company went 

 into bankruptcy and the Senator mine was closed 

 down. By 1915, Mr. George Sexton had obtained a 

 25-year lease on the New Almaden property and ap- 

 pointed W. H. Landers as general manager. 



With the beginning of Landers' management in 

 June 1915, the Senator mine was reopened, an exten- 

 sive development program was begun, and a modern 

 reduction plant was installed near the north portal of 

 the 260 level to eliminate the long haul to the 

 Hacienda. This reduction plant included the first 

 Herreshoff furnace and electrolytic dust collector ever 

 used in the recovery of quicksilver (fig. 99), and al- 

 most from the first it proved to be efficient. After 

 2 years of successful management Landers was suc- 

 ceeded by Mr. Edmund Juessen, who continued the 

 development of the mine and also added a little-needed 

 60-ton Scott furnace to supplement the Herreshoff. 

 The Scott was used only 3 weeks, for in May 1919 

 a wooden ore bin on top of it caught fire and ignited 

 the rest of the reduction plant. Mining nevertheless 

 continued with few interruptions between 1915 and 

 1926, when the mine was last closed down. During 

 this period the workings were developed to the 1300 

 level, as shown on plates 15 and 18, but as the sinking of 

 the deep inclines failed to keep pace with the removal 

 of ore, much of the ore was underhanded. The fairly 

 high rate of production maintained from 1915 to the 

 end of 1923 diminished in the next 2 years, and early 

 in 1924 the ore bodies were virtually exhausted. The 

 company then did 1,870 feet of exploratory diamond 

 drilling from the 300, 400, 500, 1000, 1100, and 1200 

 levels, but failed to find new ore shoots, and on 

 March 11, 1926, the Senator mine was closed down. 

 The record of its production is confused by the in- 

 clusion of ore mined at the New Almaden mine, but 

 the total production probably was a little more than 

 20,000 flasks. 



Since 1926 lessees have reworked the dumps, hand 

 sorting the coarser material and using various concen- 

 trating devices to recover the fine cinnabar, but the 

 amount of quicksilver they have been able to retort 

 from this concentrated ore has been small. In the 

 summer of 1948 the old Herreshoff furnace was de- 

 molished, principally for scrap iron and usable brick, 

 but some of the bricks from the lower part of the 

 furnace lining were found to contain enough quick- 

 silver to justify treating them in a retort. 



