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Blue Jay Mine (Blue Jay claim; Blue Bird Mine; McKnight; McKnight), Three Forks, Coastal Range, Trinity Co., California, USA

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A former Mn-Cu-Fe-silica mine located in sec. 8 & in the NW¼ sec. 17, T26N, R12W, MDM, on the SE slope of Hayden Roughs, in the Mad River area (just over the W side of the divide between the Mad and Eel Rivers), on Bureau of Land Management wilderness land (Yolla Bolly-Middle Eel Wilderness) (located claim). MRDS database stated accuracy for this location is 1,000 meters.

Mineralization is a sedimentary Mn deposit hosted in Late Cretaceous chert. The ore body is lenticular, disseminated and irregular, strikes N30W and dips 60N at 1.0 to 1.22 meters thick, at 5 meters wide and 100 meters long. The primary mode of origin is sedimentation and the secondary mode is residual concentration. Primary ore control was faulting and secondary was bedding. There is no wallrock alteration. Local rocks include Franciscan Complex, unit 1 (Coast Ranges).

The Mn ore occurs in 2 beds averaging 3 to 4 feet in thickness, about 15 feet apart, enclosed in thin-bedded Franciscan chert. The strike on the E slope of the ridge is N55W, dipping 60 to 75 NE. This trend continues W to the ridge crest where a fault striking N50E and dipping 55SE displaces the beds slightly. W of the fault the beds strike N20 to 30W and dip 20 to 30 NE. A thin greenstone body exposed was apparently injected along contact of the chert and sandstone. NW of the greenstone, the chert merges along strike with the sandstone. The ore is largely primary, as surface oxidation forms black oxide coating 1 to 2 inches thick. The primary ore is mostly reddish-brown hausmannite, cut by rhodochrosite veinlets, or hydrous silicates. Quartz veins carry some chalcocite. Secondary Cu minerals present are native copper, cuprite and malachite.

Analytical data results: The primary ore grade is 50 to 55% Mn, 6 to 10% silica, and 3 to 9% CO2.

Mineral List

19 entries listed. 17 valid minerals.

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O’Brien, J.C. (1943), Current notes on activity in the strategic minerals, Redding field district: California Division Mines Report 39: 84.

Taliaferro, Nicholas Lloyd & F.S. Hudson (1943), Genesis of the manganese deposits of the Coast Ranges of California: California Division Mines Bulletin: 269.

Trask, Parker Davies, Ivan F. Wilson & F.S. Simons (1943), Manganese deposits of California – a summary report: California Division Mines Bulletin 125: 59, 196.

Trask, Parker Davies (1950) Geologic description of the manganese deposits of California. California Division of Mines Bulletin 152, 378 pp.: 303, 308-310.

Trengrove, Russell R. (1960), Reconnaissance of California Manganese Deposits, U.S. Bureau of Mines Report of Investigation 5579.

O’Brien, J.C. (1965) Mines and mineral resources of Trinity County, California. Caifornia Division of Mines and Geology County Report 4: 125 pp.: 62.

Murdoch, Joseph & Robert W. Webb (1966), Minerals of California, Centennial Volume (1866-1966): California Division Mines & Geology Bulletin 189: 159, 215, 321.

Longwill, W.D. (1979) Mineral Resources of Yolla Bolly area, Trinity County, California.

Longwill, Warren D. (1981), Mineral Resources of the Big Butte-Shinbone (5145), East Fork (5226), Murphy Glade (5298), and Wilderness Contiguous (5137) Rare II Proposed Addition to the Yolla Bolly-Middle Eel Wilderness, Trinity, Tehema, and Mendicino Counties, California.

Blake, Jr., M.C., Jayco, A.S., Leszcykowski, A.M., Longwill, Warren D., and Gobla, Michael (1983), Mineral Resource Potential maop of the Yolla Bolly-Middle Eel Wilderness and Adjacent Roadless Areas, Northern California; USGS Miscellaneous Field Studies map 1595-B.

Pemberton, H. Earl (1983), Minerals of California; Van Nostrand Reinholt Press: 49-50, 167, 182, 414.

Huebner, J. Stephen; Flohr, Marta J. (1990) Microbanded manganese formations; protoliths in the Franciscan Complex, California; USGS Professional Paper 1502.

USGS (2005), Mineral Resources Data System (MRDS): U.S. Geological Survey, Reston, Virginia, loc. file ID #10072355, 10109404 & 10214554.

Longwill, W.D., Information from personal files, WFOC, Spokane, WA.

WFOC MPF No. 0061050017.

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