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Long Ledge No. 1 Mine (Wood's Mine; Grizzly Bear Mine; Wood's Grizzly Bear Mine), Long Ledge group, Hog Mountain, Fresno Co., California, USA

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A former Cr-Fe occurrence/mine located in sec. 24, T12S, R24E, and in sec. 19, T12S, R23E, MDM, 2.0 km (1.2 miles) SE of Hog Mountain (coordinates of record), on the SE end of the mountain, S of Trimmer, on National Forest land (located claim). Discovered and first operated in 1916. Owned by G. E. Wood and John Mcgirr, California, last operators (1976). No mining since 1918. MRDS database stated accuracy for this location is 10 meters.

Mineralization is hosted in dunite. Associated rocks include gabbro. The ore body is a linear pod/lens in form, disseminated tabular, and irregular. It strikes N15W, dips 85E at a thickness of 1.83 - 3.0 meters, a width of 3.05 - 8.0 meters, and a length of 84.0 meters. The primary mode of origin was magmatic differentiation. Primary ore control was lithology and the secondary control was igneous activity. Wallrock alteration is intense (carbonitization0. Local alteration is serpentinization. Local rocks include Mesozoic gabbroic rocks, unit 2 (undivided) and/or ultramafic rocks, chiefly Mesozoic, unit 2 (Western Sierra Nevada and Klamath Mountains).

The chromite deposits of Watts Valley occur on the eastern limb of a synclinal, NE-plunging, ultramafic sill. The eastern limb, known as Hog Mountain, is a little over 1 mile wide, while the western limb, which forms Red Mountain, averages 3 miles wide. The 2 limbs join to the NW and together form a discontinuous, triangular exposure of peridotite 10 miles long and 8 miles wide across the base.

Local geologic structures include: A shear zone that trends N15W through the deposit.

Workings include surface and underground openings comprised of 2 co-linear open cuts, each 60 feet long. The cuts are 70 feet apart on a line N10W. BETWEEN THEM LIES A small prospect pit and several piles of ore lie between the cuts. An open adit and shaft are located at the N end of the upper cut.

Production data are found in: Stinson, Melvin Clarence (1975).

Production statistics: Year: 1918 (period = 1915 [?] - 1918); ore estimated at ^33% Cr2O3.

Reserve-Resource data are found in: Rynearson, Garn Arthur (1948): 93. Rynearson estimated that a block of ore 275 X 25 X 10 feet still remains in the deposit as a massive and disseminated block of chromite.

Reserves and resources data: Year: 1948; estimated at 3,000 metric tons of ore (5.0% Cr).

Mineral List

5 entries listed. 2 valid minerals.

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Rynearson, Garn Arthur (1948), Chromite deposits of Tulare and eastern Fresno Counties, California: California Division Mines Bulletin 134 part 3, chapter 3: 91-93, 101, Pl. 6.

Stinson, Melvin Clarence (1975) California Division of Mining and Geology Mineral Property Report (unpublished).

USGS (2005), Mineral Resources Data System (MRDS): U.S. Geological Survey, Reston, Virginia, loc. file ID #10043381, 10110662 & 10138885.

U.S. Bureau of Mines, Minerals Availability System (MAS) file ID #0060190220.

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