MINES 



127 



ported to the kiln in Guadalupe Canyon by a gravity 

 pulley. It was fired in a conical kiln said to have been 

 100 feet in diameter at the base and 60 feet high ; a 

 single charge yielded 160 barrels of lime and required 

 41/2 cords of wood for its firing. Part of the lime so 

 produced was sufficiently pure to be used in sugar 

 refining, and doubtless a part was used at the mines 

 in the recovery of quicksilver. 



Cement is being made from limestone of the Fran- 

 ciscan group at the quarry of the Permanente Cement 

 Co., only a few miles north of the New Almaden dis- 

 trict. The limestone of like age in the district is 

 apparently similar and in places even purer, but oc- 

 curs in smaller bodies. Because of the general scarcity 

 of limestone in the region, at some time in the future 

 limestone may be quarried from some of the larger 

 lenses in the New Almaden district for use in the 

 manufacture of cement. 



Eocene limestone has been quarried from time to 

 time since 1915 (Huguenin and Costello, 1921, p. 185) 

 from a small quarry 1,000 feet southeast of the Bernal 

 mine in the Santa Teresa Hills. It is reported 

 (Logan, 1947, p. 311) to have been used chiefly for 

 fertilizer in recent years, but in 1917 it was quarried 

 for use in sugar refining. An analysis of this lime- 

 stone follows (Huguenin and Costello, 1921, p. 185). 



Analysis of Eocene limestone from Santa Teresa Hills 

 [Analyst unknown] 



SiO 2 2.50 



A1 2 3 11.24 



Fe 2 O 3 2.90 



MgO 1.55 



CaCO, _ - 80.81 



Total 99.00 



SERPENTINE 



Serpentine has been quarried in the New Almaden 

 district about 12,000 feet northeast of the apex of 

 Mine Hill for use in the manufacture of fused phos- 

 phate fertilizer. In 1947 the Permanente Metals Corp. 

 trucked 10,000 tons of serpentine from this quarry to 

 its plant at Permanente, Calif., where the serpentine 

 was charged into an electric furnace with a fixed pro- 

 portion of phosphate rock from Idaho, and the mix- 

 ture then melted, tapped, and quenched. The resultant 

 material, which was guaranteed to contain 18 percent 

 of available PaOs, was sold as a phosphate fertilizer. 

 The quarry site was selected primarily because of its 

 accessibility, but the magnesia-silica ratio of the ser- 

 pentine body there is slightly greater than the average 

 for the other serpentine masses in the district. In 

 1948, the magnesian phosphate fertilizer was no longer 

 being made, and the quarry was not being used. 



GRAVEL. SAND, AND LOAM 



Aggregate materials and loam are quarried by two 

 companies from the bed of Los Gatos Creek in sec. 16, 

 T. 8 S., R. 1 W., in the northwest corner of the dis- 

 trict. The gravel and sand are used locally for con- 

 crete, septic tanks, and road metal. The loam, which 

 is taken from the northernmost deposit, is in demand 

 on the San Francisco Peninsula for use as foundation 

 material for lawns and gardens. 



The northern deposit is owned by W. R. Burchell, 

 of San Jose, Calif., and operated under the name of 

 the Los Gatos Sand and Gravel Co. Mr. Burchell 

 has quarried in the area since 1926, at which time he 

 bought the property from the Tiffany Bros. Gravel Co. 

 In 1936 the Vasona percolation dam was built just 

 downstream from his plant, and the damming of flood- 

 stage waters resulted in the accumulation of a 10-foot 

 layer of gravel, sand, and loam in the following 4 

 years. This material, particularly the fine loam that 

 contains abundant decayed plant fragments, has fur- 

 nished the bulk of the production of gravel and sand 

 in recent years. 



The southern deposit has been operated since 1947 

 by the Los Gatos Aggregate and Materials Co., owned 

 by A. Johnson and Glenn Reinhart of Los Gatos. 

 They own 13 acres of ground, 7 of which contain 

 workable gravel to a depth of 30 feet, and lease 10 

 acres from the town of Los Gatos. 



ROAD METAL 



Chert of the Franciscan group has been quarried 

 for road metal at the northern base of the Santa 

 Teresa Hills, west-northwest of the Santa Teresa mine. 

 The chert in this area required no crushing, because 

 of its rhythmic bedding and the abundance of frac- 

 tures at right angles to the bedding. Only a small 

 amount of it has been quarried here for local use, but 

 elsewhere in the California Coast Ranges chert has 

 been used rather extensively because it makes a vir- 

 tually indestructible road surface. 



Burned mercury ore, usually referred to as "cal- 

 cines," from the old Hacienda, has been used in sur- 

 facing the roads in the New Almaden mine area. This 

 material, which tends to cement itself on repeated 

 wettings, forms road surfaces that are hard and well 

 drained but somewhat dusty when dry. 



MINES 



The principal mines of the New Almaden district 

 lie along the 5-mile stretch of Los Capitancillos Ridge 

 between Almaden Canyon on the southeast and Guada- 

 lupe Canyon on the northwest. The west end of the 

 mineralized zone is a part of the Guadalupe mine 



