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Longfellow Mine (Ofarizona Copper Co. group [in part]; Longfellow incline), Clifton, Copper Mountain District (Clifton-Morenci District), Shannon Mts, Greenlee Co., Arizona, USA

Azurite
Longfellow Mine, Clifton, Copper Mountain District, Shannon Mts, Greenlee Co., Arizona, USA

Photo: Rob Lavinsky
Latitude: 33°5'3"N
Longitude: 109°21'29"W
A former surface and underground Cu-Au-Ag-clay mine located in the NE¼SE¼ & in the SE¼NE¼ sec. 16, and in the W½NW¼ sec. 15, T4S, R29E, in the Morenci open pit just N of Modoc Mountain. The upper workings of the Longfellow ore body extend over the East Yankee, Longfellow, and Longfellow Extension claims. Discovered by Robert Metcalf in 1872. Produced 1882-1932. Owned and operated by the Phelps Dodge Corp., Morenci Branch (as part of the Morenci Open Pit). Prior operators included the Longfellow Extension Copper Co.; the Arizona Copper Co. Ltd.; Leszynsky Brothers; and the Longfellow Mining Co.

Mineralization is an irregular ore body hosted in the Longfellow Limestone and Morenci Shale. The ore zone is 121.92 meters wide with a depth to bottom of 121.92 meters. Ore control was a funnel-shaped mass that occurs between two large porphyry dikes. Irregular and tabular deposits of very rich oxidized ores along the contact between limestone and porphyry. Associated rock units are the Coronado Quartzite and the Morenci Granite Porphyry. Ore concentration was secondary enrichment along sedimentary rock and porphyrycontacts, and between dikes. The porphyry dikes are somewhat mineralized but have no economic value. Mineralization was partially facilitated by the fault.

The principal stopes between the north and middle dikes displayed essentially cuprite with small amounts of manganese dioxide while stopes between the middle and south dikes showed copper carbonates with large amounts of black manganese. Pure kaolin occurs extensively in the mine. The Cu ore bodies narrow with depth.

Alteration is sericitized porphyry. The Morenci shale shows hardening and introduction of epidote. The limestone contains seams of magnetite intergrown with pyrite, chalcopyrite and prisms of pyroxene. Substantial surface oxidation to limonite and kaolin is present.

Local structures include a well-defined fault with strike of N65°W and upthrow on the south side of 80 to 100 feet. Three main porphyry dikes that trend ENE, widen considerably with depth (from 20 feet wide on surface to 90 feet wide at depth), and send out horizontal sheets in the lower part of the Longfellow Limestone. Ore bodies in the region tend to follow porphyry contacts.

Workings total 646.18 meters long and 137.16 meters deep. Developments included tunnels on 4 levels, stoping, open pit mining, one incline with a vertical run of about 80 feet.; The section of the Longfellow workings that lies on the East Yankee claim was developed by 4 levels from the East Yankee shaft (Detroit Copper Mining Co. of Arizona). A 1300 foot tunnel was driven from Chase Creek connects with a 600 foot blind shaft (winze).

Mineral List

Azurite
Chalcocite
Chalcopyrite
Copper
Cuprite
Epidote
'Garnet'
'Hornblende'
Kaolinite
Limonite
Magnetite
Malachite
Pyrite
Sphalerite
Tremolite


15 entries listed. 12 valid minerals.

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References

Kunz, G.F. (1885), On remarkable copper minerals from Arizona, Annals of the New York Academy of Science: 3: 275-278.

Farrington, O.C. (1891), On crystallized azurite from Arizona, American Journal of Science: 41: 300-307.

Dana, E.S. (1892) System of Mineralogy, 6th. Edition, New York: 297, 1094.

Lindgren, W. (1903), The copper deposits of Clifton, Arizona, Engineering and Mining Journal: 75: 705

Lindgren, W. (1904), The genesis of copper deposits, Engineering and Mining Journal: 78: 987.

Lindgren, W. (1905), The copper deposits of the Clifton-Morenci district, AZ, USGS PP 43: 233-239.

Stevens, P. (1911) The Copper Handbook: Vol. X: 356-357, Arizona Copper Co. Ltd.

Reber, L.E., Jr. (1916), The mineralization at Clifton-Morenci, Economic Geology: 11: 528-573.

University of Arizona Bull. 41 (1916-17), Mineralogy of Useful Minerals in Ariaona: 23;, 42, 44.

Weed, W.H. (1918) The Mines Handbook, Vol. XIII: 470, Arizona Copper Co. Ltd.

Tenny, J.B. (1927-1929) History of Mining in Arizona, Special Collection, University of Arizona Library & Arizona Bureau of Mines Library: Vol. 1: 97.

Schwartz, G.M. (1934), Paragenesis of the oxidized ores of copper, Economic Geology: 29: 55-75.

Grout, F.E. (1946), Microscopic characters of vein carbonates, Economic Geology: 41: 475-502.

Cleland, Robert G. (1952) A History of Phelps Dodge.

Dunning, C.H. (1959) Rock to Riches: 116-118.

Galbraith, F.W. & D.J. Brennan (1959), Minerals of AZ: 55, 108.

Bideaux, R.A. (1973), The collector (on azurite), Mineralogical Record.: 4: 34-35.

Bennett (1975) Geology and Origin of the Breccias in the Morenci-Metcalf District, Greenlee County, Arizona, MS thesis, University of Arizona, 153 pp.

Phillips, K.A. (1987), Arizona Industrial Minerals, 2nd. Edition, Arizona Department of Mines & Minerals Mineral Report 4, 185 pp.

Anthony, J.W., et al (1995), Mineralogy of Arizona, 3rd.ed.: 125, 266, 286.

USGS Clifton Quadrangle map.

U.S. Bureau of Mines - Arizona Bureau of Geology and Mining Technology production file data.

USGS Geologic Atlas Clifton Folio Arizona (1905) - Economic Geology Map.

U.S. Bureau of Land Management Mining District Sheets #840 & #839.

MRDS database Dep. ID #10048281, MRDS ID #M800406; and Dep. ID #10209853, MAS ID #0040110135.

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Copyright © Jolyon Ralph and Ida Chau 1993-2014. Site Map. Locality, mineral & photograph data are the copyright of the individuals who submitted them. Site hosted & developed by Jolyon Ralph. Mindat.org is an online information resource dedicated to providing free mineralogical information to all. Mindat relies on the contributions of thousands of members and supporters. Mindat does not offer minerals for sale. If you would like to add information to improve the quality of our database, then click here to register.
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