152 



GEOLOGY AND QUICKSILVER DEPOSITS, NEW ALMADEN DISTRICT, CALIFORNIA 



155 feet below. The aggregate length of all the known 

 workings is only a little more than 2,000 feet. 



In this same general area are other workings which 

 may conveniently be dismissed with the Providencia 

 mine, though they are actually separate prospects. 

 These include the Soda Springs tunnel (1,000 feet 

 west of the Lower Providencia), the Yellow Kid Jr. 

 workings (southeast of the Lower Providencia tun- 

 nel), and the Prospect shaft No. 2 (1,900 feet east of 

 the Lower Providencia tunnel). 



History and production 



The Providencia upper workings are said to have 

 yielded "several thousand cargas [1 carga = 300 

 pounds] of superior ore," which was treated in the 

 Enriquita furnace during the period 1861-63. In 

 1864 the Lower Providencia tunnel was driven to 

 explore beneath the upper levels, but it failed to re- 

 veal any ore and probably never even reached the 

 downward projection of the ore-controlling struc- 

 tures. During the next several years some additional 

 ore was found in small pockets in the upper work- 

 ings, but when the Enriquita mine closed down in the 

 late 1870's activity at the Providencia mine also came 

 to a stop. 



In 1882, however, the Providencia ledge was pros- 

 pected farther east ; the Prospect shaft No. 2 was sunk 

 to a depth of 202 feet, and from its bottom a drift, 

 was extended along the ledge for 300 feet and a 

 crosscut run north "through the ledge for over 100 

 feet.*' This work disclosed some cinnabar but no ore. 

 In the following year the Soda Springs tunnel, to the 

 south, whose portal was near an active spring de- 

 positing tufa, was driven 217 feet but struck no ore. 

 Nine years later, in 1898, the Yellow Kid Jr. pros- 

 pects southeast of the Lower Providencia tunnel 

 yielded 170 tons of high-grade ore, but other adits 

 driven nearby apparently were unproductive. In 

 1909, in an attempt to revive the Providencia mine, 

 the Lower Providencia tunnel was extended 213 feet 

 to serpentine, but, as a drift for 80 feet extending 

 along the contact traversed only barren silica-car- 

 bonate rock, the project was abandoned. In 1942 

 some bulldozer work was done on the surface, but 

 again no ore bodies were discovered. 



The total production of the Providencia mine can- 

 not be determined from available records, but it prob- 

 ably is less than 2,000 flasks of quicksilver. 



Geology 



The upper workings of the Providencia mine ex- 

 plore a conspicuous ledge of silica-carbonate rock that 

 strikes nearly east-west. (See pi. 1.) This ledge 

 dips 45-60 N. where exposed in the Upper Provi- 



dencia tunnel, but farther east, at the Prospect shaft 

 No. -2, it stands nearly vertical or dips steeply south. 

 It is on the south, or lower, side of a serpentine sill, 

 which at the Enriquita mine to the west is mineralized 

 along its north, or upper, contact. A second body 

 of silica-carbonate rock is cut near the portal of the 

 Lower Providencia tunnel, and its extension to the 

 southeast probably contained the ore bodies of the 

 Yellow Kid Jr. workings. This body dips about 

 40 S. where it is cut in the tunnel. 



Ore bodies 



Little is known regarding the occurrence of the 

 small high-grade pods of ore found in the area. 

 Some ore was seen in the Upper Providencia tun- 

 nel just above the north-dipping footwall contact 

 -of the silica-carlxmate rock, and ore removed from 

 an opencut above apparently also lay above the foot- 

 wall. If the area just above this footwall contact is 

 the most favorable place for deposition of ore in the 

 Providencia mine area, many of the upper adits, which 

 began above the footwall, failed to test the best pos- 

 sibilities of the area. 



ENRIQUTTA MOTE 



Location and extent of workings 



The Enriquita mine, which was the second most 

 productive of the "outside" mines on the New 

 Almaden property, lies about 2 miles northwest of 

 Mine Hill, on the steep south slope of Los Capitan- 

 cillos Ridge. The workings extend from close to the 

 top of the ridge down to the Eldredge tunnel, which 

 is so close to the level of Guadalupe Creek that it is 

 periodically flooded by waters impounded behind the 

 Guadalupe Dam. These workings were virtually all 

 inaccessible when this study was made, but according 

 to available maps they consist mainly of more than 

 9,000 feet of drifts and crosscuts distributed on at 

 least ten irregularly spaced levels. (See fig. 96.) 

 These were formerly reached through 3 principal 

 shafts and 6 adits, of which the lowest and longest 

 is the Eldredge tunnel. This adit and the connected 

 drifts and crosscuts were driven primarily to explore 

 beneath old stopes mined out before 1865, and they 

 constitute nearly half of the level workings of the 

 mine. Most of the higher levels are older, and their 

 position and extent are known only from several old 

 t racings which do not entirely agree. On the map 

 accompanying this report (fig. 96) a few of the shorter 

 levels of unrecorded altitude have been omitted for 

 simplification. 



History and production 



The Enriquita mine was first worked in 1859, and 

 it is said to have yielded 10,571 flasks in the next 4 



