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School Girl and Union Mine (School Girl & Union; Springfield), Logtown, El Dorado District, Mother Lode Belt, El Dorado Co., California, USA

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A former lode Au occurrence/mine located in sec. 12, T9N, R10E, MDM, about Logtown, along the E side of Martinez Creek, S of Tombstone Mountain (2 miles SSE of El Dorado), on private land. MRDS database stated accuracy for this location is 1,000 meters.

Mineralization is a vein/ore shoots deposit hosted in slate. The ore body strikes N16E and dips 69S. There are 5 veins 5 to 10 feet thick on average. The dip is 60 to 79E. The main, or Springfield, shaft, which is 320 feet E of the hanging wall of the vein at surface, crosses the vein at the 1,200 foot level. W Gouge vein also crossed 60 feet above the 1,600 foot level. The vein breaks into stringers further N. Another vein occurs to the E. Local rocks include Jurassic marine rocks, unit 1 (Western Sierra Nevada and Western Klamath Mountains).

Workings include underground openings comprised of a main shaft 1,640 feet deep; the Clement shaft 900 feet deep on an incline of 70 degrees. Over 21,000 feet of drifts were also reported to exist.

Production data are found in: Logan, Clarence August (1934).

Records were never disclosed. Production was believed to have been over estimated, in most cases.

Production statistics: Year: 1867 (period = ____ to 1867), estimated: 41 grams Au/metric ton.

Mineral List



6 entries listed. 6 valid minerals.

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References

Emmons and Becker (1885) Statistics and Technology of the precious Metals. Census reports Tenth census. June 1, 1880, Volume 13 By United States. Census office. 10th census, 1880, United States. Census Office.

Logan, Clarence August (1934), Mother Lode Gold Belt of California: California Division Mines Bulletin 108, 221 pp.: 42-43, Pl. II.

Logan, Clarence August (1938), Mineral resources of El Dorado County: California Journal of Mines and Geology, California Division Mines (Report 34): 34(3): 267.

USGS (2005), Mineral Resources Data System (MRDS): U.S. Geological Survey, Reston, Virginia, loc. file ID #10006900 & 10187543.

U.S. Bureau of Mines, Minerals Availability System (MAS) file #0060170281.

 
Mineral and/or Locality  
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