164 



GEOLOGY AND QUICKSILVER DEPOSITS, NEW ALMADEN DISTRICT, CALIFORNIA 



ore and 40 tons of coarse ore per day, began unwater- 

 ing the old mine through the Engine shaft, and re- 

 sumed mining on a modest scale. In 1906 the company 

 was reorganized under the name of the New Guadalupe 

 Mining Co., with Davey as president, and within 2 

 years it brought the productive rate of the mine up 

 to a relatively high level that was maintained until 

 1918. During this period the New, or Guadalupe, 

 Inclined shaft was sunk and workings were driven 

 from it, the Old Hill mine and neighboring areas were 

 further developed, and the north slope of Los Capi- 

 tancillos Ridge was explored for the first time by 

 several adits and pits. While all this development 

 was under way on the ridge, an attempt was being 

 made to un water the old mine south of the creek; but 

 it proceeded slowly because of the copious seepage 

 from Guadalupe Creek. To overcome this difficulty, 

 the company in 1917 lined the creek bed with a con- 

 crete flume 740 feet long and 55 feet wide, and with 

 side walls 9 feet high. In 1920, however, when the 

 mine was unwatered only to the No. 7 level and the 

 stopes were still inaccessible, the pumps failed, and 

 unwatering of the old mine was abandoned. In 1922 

 the entire mine was closed down after a third period 

 of activity had yielded 33,214 flasks. During the in- 

 active period which followed, the title first passed 

 to Mrs. J. S. Gregory by legal action, and then in 

 1927 it became the property of Albert and Frank 

 Golden. In 1930 a little quicksilver was recovered 

 through retorts by a lessee, Hernandez, from a cleanup 

 of the Scott furnaces. 



In 1935 the Laco Mining Co., composed of H. N. 

 Mason, George F. Kirk, and others, obtained a lease 

 from the Golden brothers, and after building a small 

 retort it began the fourth period of production from 

 the mine by reworking some of the old dumps. When 

 in 1937 the Golden brothers lost a lawsuit to Mrs. J. S. 

 Gregory, the Laco Mining Co. obtained a lease from 

 her. They then constructed four additional two-pipe 

 retorts near the Guadalupe incline shaft, and in 1943 

 installed the modern reduction plant. In the same 

 year the discovery of a new body of ore at the surface 

 between the new plant and the Guadalupe Inclined 

 shaft led to openpit operations, which yielded most 

 of the ore furnaced during, the next 4 years; some 

 additional ore was obtained, however, from the upper 

 workings connected with the shaft, from the Kelly 

 and New Prospect areas near the crest of the ridge, 

 and from the old dumps. In 1947 the Laco Mining 

 Co. gave up its lease, after having recovered only 

 3,499 flasks during its 12-year period of operation, 

 and in 1948 the mine was again idle. 



A comparison of the mine's annual production with 

 the annual price of quicksilver indicates that the more 

 significant peaks in production have resulted largely 

 from favorable conditions within the mine rather than 

 from increases in the price of quicksilver. The 

 greatest period of production, however, from 1875 

 to 1881, apparently was terminated by an abrupt de- 

 crease in price before 1880. The second productive 

 peak, in 1912, was brought about by the discovery of 

 new ore deposits, though production during the latter 

 part of this period may have been stimulated by the 

 price rise during World War I. The comparable in- 

 crease in the value of quicksilver during World 

 War II gave rise to only a relatively small annual 

 production, which, however, was several times that of 

 the years between the wars. 



Mine workings 



The workings of the Guadalupe mine consist of 

 about 30,000 feet of level workings, 5 main shafts. 

 more than a dozen stopes, and several thousand square 

 feet of openpits that lie within an area of a little more 

 than a quarter of a square mile. (See pi. 15.) The 

 mine is sharply divided into two parts a compact 

 older group of underground workings lying mainly 

 south of Guadalupe Creek and known as the Old Mine, 

 and the newer more scattered workings underlying 

 Los Capitancillos Ridge north of the creek. 



The older part of the mine was inaccessible when 

 the field investigation leading to this report was made. 

 It was originally developed through 5 vertical shafts 

 and 1 inclined shaft, all put down near Guadalupe 

 Creek. The largest of these was the three-compart- 

 ment vertical Engine shaft,, sunk from a terrace 30 

 feet above the creek to a depth of 620 feet, where it 

 bottomed on the No. 6 level. From this level an in- 

 clined winze extended to a depth of about 830 feet 

 below the creek bed, or 464 feet below sea level, to the 

 No. 10 level, the deepest in the mine. The other ver- 

 tical shafts, known as the Maryland shafts Nos. 1 

 and 2, the Virginia shaft, and the Lamb shaft, con- 

 nected the extremities of some of the upper drifts 

 with the surface. The collar of the Old Inclined 

 shaft was on the north bank of the creek near the 

 bridge, and its bottom on the No. 2 level nearly 300 

 feet southwest of the collar and 280 feet lower. The 

 level workings from these shafts total about 13,000 

 feet in length and consist of 14 main levels, although 

 only the lower 11 of these are numbered. The ver 

 tical intervals between levels do not exceed 100 feet, 

 and some are considerably less. As shown on the old 

 company maps and cross sections nearly all the levels 



