64 



California Division of Mines and Geology 



Bull. i97 



numerous granitic dikes and possible schist interbeds, 

 particularly in the topographically low areas. Two 

 samples, one (GP-23) analyzed by Abbot A. Hanks, 

 Inc., in 1955 and the other (KH-1) by the Division of 

 Mines and Geology laboratory in 1964, indicate the 

 high quality of the dolomite: 



li;n 

 Sample SiOs FeiOg AI2O3 C3O MgO PsOs K2O loss 

 GP-23 .... 0.14% 0,11% 0.17% !0.80% 21.15% tr. n.d. n.d. 

 KH-1 1.40 0.12 0.00 M.OO 20.00 0.02% 0.00% 46.10% 



Sample GP-2 3 (Bowen and Gray, 1959, p. 35) is from 

 the central part of the pendant and KH-1 is from a 

 road cut in the main northeast salient. 



Reserves of dolomite cannot be estimated without 

 more data. At the crest of the low spur near the south- 

 east boundary of the property, a drill hole reportedly 

 bottomed in dolomite at a depth of 180 feet. Consider- 

 ing that the pendant is exposed through nearly 1,000 

 feet of relief, accessible dolomite reserves mav amount 

 to several million tons. Additional, but much smaller, 

 reserves are available to the northeast where a lens is 

 exposed in a roadcut near N'/i cor. sec. 3. 



Los Vergeles deposits. Location: N'/j T. 13S., 

 R. 3 E. and R. 4 E., M.D., 3 to 5 miles south and south- 

 west of San Juan Bautista; San Juan Bautista 15- 

 minute quadrangle. Ownership: Los \'ergeles Rancho 

 in part (1959). 



A series of small to medium-sized lenses and bodies 

 of carbonate rock comprise a gently sinuous belt that 

 lies mainly within the Los Vergeles Rancho in Monte- 

 rey and San Benito Counties. The belt extends 6 miles 

 eastward from S'/; sec. 10, T. 13 S., R. 3 E. (proj.), near 

 Crazy Horse Canyon Road, to SE'/ sec. 15, T. 13 S., 

 R. 4 E., near Queen Canyon (plate 2). The carbonate 

 rock is associated with other metamorphic rocks of the 

 Sur Series which occur as roof pendants in granodior- 

 ite (Allen, 1946, p. 20). 



According to Bowen and Gray (1959, p. 23), the 

 carbonate rock consists largely of crystalline lime- 

 stone but is extensively contaminated with silica and 

 dolomite. The limestone varies from coarse to fine 

 crystalline and from blue gray to white. A select sam- 

 ple of white, coarse-crystalline limestone, collected 

 from the carbonate body crossed by San Juan Grade 

 road and analvzed by Abbot A. Hanks, Inc., in 1958, 

 contained 55.48% CaO, 0.25% MgO, 0.18% SiOj, 

 0.03% FeaOa, 0.08% AI2O3, and 0.02% P2O5. In spite of 

 the analysis, it is evident that careful sampling and 

 selective mining would be required to develop lime- 

 stone of uniform grade. The largest bodies reportedly 

 lie at the west end of the belt near Crazy Horse (Can- 

 yon. 



Apparently, there has been only minor develop- 

 ment of one of the deposits. A small tonnage of lime- 

 stone was produced from a quarry along the San Juan 

 Grade road near W'/ corner sec. 18, T, 13 S., R. 4 E. 

 (proj.). Some of this material was used by the Judson 



Iron Works, presumably as a steel flux (Laizure, 1925, 

 p. 43). 



Martin Ranch deposits. Location: Sees. 32, 33 and 

 34, T. 13 S., and N'/^ sec. 4, T. 14 S., R. 5 E. (proj.), 

 M. D., 6 to 7 miles south of Hollister; HoUister and 

 Gonzales 15-minute quadrangles. Ownership: Martin 

 brothers, 1215 Guarantee Savings Building, Fresno, 

 California (1966). 



Numerous small to medium-sized bodies of crystal- 

 line dolomite and limestone lie on the 2,800-acre Mar- 

 tin Ranch. The dolomite deposits are largely confined 

 to the south part of the ranch in the vicinity of N'/ sec. 

 4 (proj.). Limestone deposits lie north and northwest 

 of there — mainly in sees. 32 and 33 (proj.). The only 

 commercial development was by A. J. Fazzi who was 

 preparing to ship dolomite from an unidentified 

 deposit on the Martin Ranch in June 1916 (Bradley 

 and Logan, 1919, p. 635-636; Logan, 1947, p. 278). 



The distribution of the Martin Ranch dolomite and 

 limestone, based largely on the detailed mapping of 

 Thomas H. Rogers (1968, unpublished map), is in- 

 dicated on plate 2. 



The main dolomite deposit in NE'/ sec. 4, examined 

 briefly in February 1964, covers a north-trending area 

 about 1,200 feet long by at least 200 feet wide. The 

 deposit does not appear to be solid dolomite at its 

 north end, where it is bordered and intruded by gra- 

 nitic rock. To the south, the dolomite gives way to 

 limestone (see Reeves Northeast deposits). Most of 

 the dolomite is white and medium to very coarse crys- 

 talline. There is some iron oxide staining along joints 

 and fractures; otherwise, the dolomite appears to be of 

 uniform, high quality. The deposit was explored in 

 1956 by Westvaco Mineral Products Division, EMC 

 Corporation, who made five or six bulldozer cuts 

 across the long axis of the body. Four chemical analy- 

 ses of dolomite from the cuts were made by Abbot A. 

 Hanks, Inc., in 1958 (Bowen and Gray, 1959, p. 35) 

 and show the material to be of high quality: 



Another body of dolomite, exposed immediately to 

 the west, covers an irregular east-trending area with 

 maximum areal dimensions of 900 feet by 600 feet. 

 According to Thomas H. Rogers ( 1968, personal com- 

 munication), who mapped the northern part of the 

 mass, the dolomite is nearly white, coarse crystalline, 

 and pure. The outcrop pattern of the dolomite sug- 

 gests that the mass dips gently to moderately to the 

 north. 



Dolomite reserves of the above deposits are undeter- 

 mined but could amount to several million tons. The 

 two dolomite deposits are reasonably accessible and 

 well situated for mining, being exposed through 200 

 to 300 feet of relief. 



