Arizona Geological Surveyazgs.arizona.edu | repository.azgs.az.gov

OPEN-FILE REPORT OFR-19-03

Preliminary evaluation of mineral resources of the Santa Cruz Valley National Heritage

Area, Arizona

March 2019

P.A. Pearthree and F.M. Conway Arizona Geological Survey

Photo by Ken Lund - CC BY-SA 2.0

Arizona Geological Survey

P.A. Pearthree, Arizona State Geologist and Director

Manuscript approved for publication in March 2019 Printed by the Arizona Geological Survey

All rights reserved

For an electronic copy of this publication: www.repository.azgs.az.gov

For information on the mission, objectives or geologic products of the Arizona Geological Survey visit azgs.arizona.edu

This publication was prepared by the Arizona Geological Survey at the University of Arizona. The University of Arizona, or any department thereof, or any of their employees, makes no warranty, expressed or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or pro-cess disclosed in this report. Any use of trade, product, or firm names in this publication is for descriptive purposes only and does not imply endorsement by the University of Arizona.

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Recommended Citation: Pearthree, P.A. and Conway, F.M., 2019, Preliminary evaluation of mineral resources of the proposed Santa Cruz Valley National Heritage Area, Arizona. Arizona Geological Survey Open-File Report OFR-18-03, 7 p.

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Introduction

In March 2019, President Donald Trump signed a public lands bill creating the Santa Cruz Valley National Heritage area in Santa Cruz and Pima Counties. This is the culmination of more than a decade of effort on the part of U.S. Representative Raul Grijalva and others working towards cultural preservation, economic development, and geotourism in the area (Nogales International, 18 Mar. 2019).

The Santa Cruz Valley National Heritage Area (Figure 1) covers a wide swath of historic and productive porphyry copper mining in southern Arizona, and mining has long been an important of the history of this region. This report provides a brief assessment of the mineral resources of the roughly 3,600 square miles (9,378 square kilometers; 2,304,000 acres) of those portions of Pima and Santa Cruz Counties encompassed by the Santa Cruz Valley National Heritage Area.

The Arizona Geological Survey and US Geological Survey have published numerous geologic maps and reports relevant to the mineral resources of the area. See Abridged References for a list of literature resources; this is not, however, an exhaustive list of mineralogic, geologic and hydrologic resources for the Santa Cruz River Valley and environs.

Mineral assessment is largely confined to metallic minerals - copper, gold, silver, lead, zinc and molybdenum extracted from the 20 metallic mineral districts within the heritage area (Figure 2). Hundreds of mines were worked in these mineral districts historically (Figure 3). Aggregate resources, the building block of human society, are also an important component of the mineral resources of the Santa Cruz Valley area.

Location

The national heritage area is situated in the upper Sonoran Desert of Arizona’s Basin and Range Province. Mountain ranges encompassed in whole or in part, include, from north to south: the Tortolita, Santa Catalina, Rincon, Tucson, Sierrita, Santa Rita, San Cayetano, Patagonia and Pajarito Mountains. Other geographic features, from north to south: Oro Valley, Tucson Basin, Santa Cruz River, Avra Valley and Green Valley.

Mineral Resources

The footprint of the Santa Cruz Valley National Heritage coincides with the heart of southern Arizona’s porphyry copper belt. For decades, the porphyry copper mines of Arizona, including Sierrita, Mission and Twin Buttes – all of which are in the heritage zone – have contributed nearly 65% of America’s copper production (USDI Natural Resources

Revenue Data for Pima County, Arizona).

Copper ore production dominated mineral production in the heritage zone since mining began here in the 1870s (Figures 4 & 5). Over the past half century, three mines – Sierrita, Twin Buttes and Mission Mines – have produced more than 8.5M shorts tons of copper (Table 1).

Table 1. Recent copper, lead, zinc, silver and molybdenum mineral production from porphyry copper mines in the heritage area

i. Mission Mine produced more than 68.2K short tons of copper in 2017. From 1963 to 2017 more than 3.3M short tons of copper were produced here. In that same time frame, there was substantial production of lead (1,506 short tons), molybdenum (6,891 short tons), zinc (3,115 short tons) and silver (49M troy ounces).

Figure 1. Annotated bounding map of the Santa Cruz Valley Heritage Area

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ii. Sierrita Mine Complex produced ~ 80K short tons of copper in 2017. From 1970 to 2017 more than 4.2M short tons of copper were produced here. Over that same time frame, there was substantial production of molybdenum (413k short tons), lead (1,582 short tons), zinc (153 short tons), and silver (11.1 M troy ounces) and gold (4,823 troy ounces).

Twin Buttes Mine produced 49.6 short tons of copper in 1992. From 1969 to 1992 ~ 1.05M short tons were produced here. Source: D. Briggs (2018)

Table 2. Pending* Metallic Mines in the heritage area.

i. Hudbay’s Rosemont Porphyry Copper project in the Helvetia mining district. Annual production is estimated at 140K tons of copper annually during the first 10 years of production. Total life span of mine estimated at 19 years.

ii. Hermosa-Taylor Zinc-Lead-Silver Carbonate Replacement project in the Patagonia mining district. See the case study below for details of the deposit.

Pending metallic mines are scheduled to begin extracting and producing ore in the next several years.

Aggregate Resources. There are nearly 20 aggregate operations in Pima and Santa Cruz Counties. All but one resides in the heritage zone (Figure 6). Any effort to reduce or withdraw existing aggregate operations would require establishing plants at greater distance from the Tucson metropolitan center; the second largest population center in Arizona. Transportation costs of aggregate and infrastructure costs (road repair) would increase proportionally with distance between Tucson and the source aggregate.

Mining Employment. In 2015, the US Dept. of the Interior reported 2,230 workers employed in copper mining and related activities in Pima County. Mining employment represents about 1 percent of employment in Pima County. Jobs in the mining industry, however, frequently pay substantially better than do jobs in the service or tourism industries.

New mineral resources in the Patagonia Mountains: case study. Silver was discovered in the Patagonia Mountains of southeastern Arizona in the 1870s. Mining operations continued there through World War II - manganese was mined in support of the war effort- and mining was a pillar of the economy and society of southern Santa Cruz County into the 1950s. By 1964 the first pulse of mining in the Patagonia Mountains ended.

In 2010, exploration geologist Don Taylor initiated a drilling program to evaluate a suspected zinc-silver-lead, carbonate replacement deposit near Hershaw, Arizona; a once bustling mining town turned ghost town. This exploration led to the discovery of the large Hermosa-Taylor Zn-Pb-Ag deposit in the Patagonia Mining District. In 2018, Taylor was awarded the prestigious Thayer Lindsley award for ‘Best Global Discovery’ at the Prospectors and Developers Association of Canada Convention in Toronto, Canada.

A report by David Wichner of the Arizona Daily Star estimates that mineral extraction at the Hermosa-Taylor

Figure 2. Metallic Mining Districts included in the Santa Cruz Valley Heritage Area. Color coding: orange – gold with or without copper or lead; yellow – uranium in veins or fissures; brown – copper porphyry with or without molybdenum, manganese, gold and peripheral zinc, lead and silver; blue – lead, zinc and silver veins and replacements (Keith and others, 1983).

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project will pump $676 million into the Arizona economy annually. Over the 32-year life span of the mine, it would yield $21 billion in mineral products.

Table 3. Select characteristics of the Taylor Deposit, Patagonia Mtns., Santa Cruz County• 43-101 Report (1/2018): 15.2 million tons at 4.2% Zn,

4.0% Pb, and 1.6 opt silver (OPT = troy oz per ton);• Deposits reside on patented or private lands in SE

Arizona’s Patagonia Mountains;• A carbonate replacement deposit with sulfides of Zn-

Pb-Ag;• Located about 55 miles south of Tucson, Arizona.• Underground mine project;• Estimated mine life of ~32 years;• Estimated 946 M lbs of zinc equivalent and 9.5 M oz

of silver production in concentrate in first 5 years.

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For additional information on the Hermosa-Taylor project and the nearby Central silver-manganese-zinc manto oxide deposit, see the Arizona Mining website.

Summary – This brief report scratches the surface of historic and ongoing mining and mineral production within the Santa Cruz Valley Heritage Area. The recent discovery of the Hermosa-Taylor Zn-Pb-Ag deposits indicates a substantial potential for discovery of greenfield mineral resources.

Figure 3. Locations of mines in the Santa Cruz Valley Heritage Area. The red box demarcates the approximate boundary of the heritage area. Source: US Geological Survey Mineral Resources Online Spatial Data (https://mrdata.usgs.gov/)

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Figure 4. Mineral production data of metallic mineral districts of Pima County (marked by orange X) that reside in whole, or in part, in the Santa Cruz Valley Heritage Area (Keith, 1974).

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Figure 5. Mineral production data of metallic mineral districts of Santa Cruz County. The two districts not included in the heritage area are lined out in orange (Keith, 1975).

Figure 6. Aggregate plants and quarries of Pima and Santa Cruz County. All but one plant is situated in the Santa Cruz Valley Heritage Area. Data source: Arizona Mine Inspector’s Office.

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ABRIDGED REFERENCES Dozens of geologic reports and maps relevant to a com-prehensive mineral assessment of the heritage area exist. Referenced below are geologic products of the AZGS and USGS particularly relevant to mineral resource assess-ment. By no means is this an exhaustive list of pertinent literature resources.

Arizona Geological Survey PublicationsFerguson, C.A., Youberg, A., Gilbert, W.G., Orr, T.R., Richard,

S.M., and Spencer, J.E., 2001, Geologic Map of the Mount Fagan 7.5’ Quadrangle, Eastern Pima County, Arizona: Arizona Geological Survey Digital Geologic Map DGM-11, version 1.1, map scale 1:24,000, 36 p.

Ferguson, C.A., Johnson, B.J., Skotnicki, J. S., Maher, J.D., Spen-cer, J.E., Gilbert, W.G., Richard, S.M., Youberg, A., Demsey, K.A., and House, P.K., 2002, Geologic Map of the Tortolita Mountains, Pinal and Pima Counties, Arizona: Arizona Geo-logical Survey Digital Geologic Map DGM-26, version 1.0, map scale 1:24,000, 46 p.

Ferguson, A.C., Johnson, B.J., and Shipman, T.C., 2003, Geologic Map of the Batamote Hills 7.5’ Quadrangle, Pima County, Arizona: Arizona Geological Survey Digital Geologic Map DGM-32, version 1.0, map scale 1:24,000, 31 p

Johnson, Bradford J., and Ferguson, Charles A., 2007, Geologic Map of the Rosemont Area, Northern Santa Rita Mountains, Pima County, Arizona: Arizona Geological Survey Digital Geo-logic Map DGM-59, version 1.1, map scale 1:24,000, 10 p.

Johnson, B.J., Ferguson, A.C., Pearthree, P.A., and Stavast, A.W., 2003, Geologic Map of the Samaniego Peak 7.5’ Quadrangle, Pima County, Arizona: Arizona Geological Survey Digital Geo-logic Map DGM-30, version 1.0, map scale 1:24,000, 21 p.

Johnson, B.J., Pearthree, P.A., and Ferguson, C.A., 2016, Geo-logic map of the Corona de Tucson 7 ½’ Quadrangle, Pima County, Arizona: Arizona Geological Survey Digital Geologic Map DGM-115, scale 1:24,000.

Keith, S.B., 1975, Index of Mining Properties in Santa Cruz Coun-ty, Arizona. Arizona Bureau of Mines Bulletin-191, 100 p.

Keith, S.B., 1974, Index of Mining Properties in Pima County, Arizona. Arizona Bureau of Geology and Mineral Technology Bulletin 189, 161 p.

Keith, S.B., DeWitt, R.H., Troll, W. and Everson, A.B., 1983, Metallic Mineral Districts and Production in Arizona. Ari-zona Geological Survey Bulletin 194, one map plate, scale 1:1,000,000.

Pearthree, P.A., and Skotnicki, S.J., 2000, Geologic Map of the Cocoraque Butte 7.5’ Quadrangle, Pima County, Arizona: Ari-zona Geological Survey Digital Geologic Map DGM-06, version 1.0, map scale 1:24,000, 29 p.

Richard, S.M., Spencer, J.E., Ferguson, C.A., and Youberg, A., 2001, Geologic Map of the Southern Part of the Vail 7.5’ Quadrangle, Eastern Pima County, Arizona: Arizona Geolog-ical Survey Digital Geologic Map DGM-12, version 1.1, map scale 1:24,000, 31 p.

Richard, Stephen M., Spencer, Jon E., Youberg, Ann, and Johnson, Bradford J., 2003, Geologic Map of the Twin Buttes 7.5’ Quadrangle, Pima County, Arizona: Arizona Geological Survey Digital Geologic Map DGM-31, version 1.1, map scale 1:24,000.

Richard, Stephen, M., Spencer, Jon, E., Youberg, Ann, and Fer-guson, Charles, A., 2005, Geologic Map of the Rincon Valley Area, Pima County, Arizona: Arizona Geological Survey Digital Geologic Map DGM-44, version 1.0, map scale 1:24,000, 11 p.

Richard, S.M., Reynolds, S.J., Spencer, J.E., and Pearthree, P.A., 2000, Geologic map of Arizona: Arizona Geological Survey Map 35, scale 1:1,000,000.

Richard, S.M., Shipman, T.C., Greene, L.C., and Harris, R.C., 2007, Estimated depth to bedrock n Arizona: Arizona Geological Survey, Digital Geologic Map DGM-52, layout scale 1:100,000, with 9 p. text.

Shipman, Todd C., 2004, Geologic Map of the Tucson SE 7.5’ Quadrangle, Pima County, Arizona: Arizona Geological Sur-vey Digital Geologic Map DGM-43, version 1.0, map scale 1:24,000.

Skotnicki, S.J., 2001, Geologic Map of the Mescal 7.5’ Quadran-gle, Pima and Cochise Counties, Arizona: Arizona Geological Survey Digital Geologic Map DGM-09, version 1.0, map scale 1:24,000, 26 p.

Spencer, J.E., 2013, The Sonoran Desert Heritage Proposal: An evaluation of the mineral resource potential of lands pro-posed for withdrawal from mineral entry. Arizona Geological Survey Open File Report, OFR-13-03, 30 p.

Spencer, J.E., Ferguson, C.A., Richard, S.M., Orr, R.T., Pearthree, P.A., Gilbert, W.G., and Krantz, W.R., 2001, Geologic Map of The Narrows 7.5’ Quadrangle and the Southern Part of the Rincon Peak 7.5’ Quadrangle, Eastern Pima County, Arizona: Arizona Geological Survey Digital Geologic Map DGM-10, version 1.1, map scale 1:24,000, 33 p.

Spencer, J.E., Youberg, A., and Shipman, T.C., 2010, Geologic Map of the Spring Water Canyon 7.5’ Quadrangle, Pima County, Arizona: Arizona Geological Survey Digital Geologic Map DGM-79, version 1.0, map scale 1:24,000.

Spencer, E.J., Ferguson, A.C., Youberg, A., and Richard, S.M., 2003, Geologic Map of the Esperanza Mill 7.5’ Quadrangle, Pima County, Arizona: Arizona Geological Survey Digital Geo-logic Map DGM-33, version 1.0, map scale 1:24,000, 10 p.

Spencer, J.E., Lingrey, S.H., Johnson, B.J., Cook, J.P., and Richard, S.M., 2011, Geologic map of the Happy Valley 7.5’ Quadran-gle, Cochise and Pima Counties, Arizona: Arizona Geological Survey Digital Geologic Map DGM-89, version 1.0, map scale 1:24,000, 7 p.

Spencer, Jon E., and Pearthree, Philip A., 2004, Geologic Map of the Oro Valley 7.5’ Quadrangle and the Pusch Peak area, Northeastern Pima County, Arizona: Arizona Geological Survey Digital Geologic Map DGM-21, version 2.0, map scale 1:24,000.

Welty, J.W., Reynolds, S.J., Keith S.B., Gest D.E., Trapp, R.A. and DeWitt E., 1986, Mine Index for Metallic Mineral Districts of Arizona. Arizona Bureau of Geology and Mineral Technology, Bulletin 196, 96 p.

Witchner, D., 9 June 2018, Patagonia zinc mine would pump nearly $700M into Arizona economy report says; Arizo-na Daily Star, https://tucson.com/news/local/patago-nia-zinc-mine-would-pump-nearly-m-into-arizona-economy/article_25e1dcf6-a9a7-5d8b-a79f-a760ae7b8cbb.html

United States Geological Survey Publications

Brown, S.G., 1976, Components of the water budget in the Tuc-son area, Arizona, 1970-72: U.S. Geological Survey, Miscella-neous Investigations Series Map I-844-M, scale 1:250,000.

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Bultman, M.W., 2003, Time-domain electromagnetic signatures of ploymetallic vein deposits in Cottonwood Canyon area, Santa Cruz County, Arizona: U.S. Geological Survey, Open-File Report OF-2002-18, scale 1:105,000.

Bultman, M.W., and Drewes, Harald, 1996, Mineral resources, ore deposit models, and resource potential of Coronado National Forest - locatable minerals: U.S. Geological Survey, Bulletin 2083-G, scale 1:126,720.

Carruth, R.L., 1995, Cross-sectional area of the shallow alluvial aquifer at selected sites along the upper Santa Cruz River, Ar-izona: U.S. Geological Survey, Water-Resources Investigations Report 95-4112, scale 1:77,000.

De La Torre, A.C., 1970, Streamflow in the upper Santa Cruz Riv-er basin, Santa Cruz and Pima Counties, Arizona: U.S. Geologi-cal Survey, Water-Supply Paper 1939-A, scale 1:250,000.

Drewes, Harald, 1980, Tectonic map of southeast Arizona: U.S. Geological Survey, Miscellaneous Investigations Series Map I-1109, scale 1:125,000.

Drewes, Harald, 1996, Geology of Coronado National Forest: U.S. Geological Survey, Bulletin 2083-B, scale 1:126,720.

Drewes, H.D., 1981, Tectonics of southeastern Arizona: U.S. Geological Survey, Professional Paper 1144, scale 1:24,000.

Gettings, M.E., and Houser, B.B., 1997, Basin geology of the up-per Santa Cruz Valley, Pima and Santa Cruz Counties, south-eastern Arizona: U.S. Geological Survey, Open-File Report OF-97-676, scale 1:250,000.

Gettings, M.E., 1996, Aeromagnetic, radiometric, and gravity data for Coronado National Forest: U.S. Geological Survey, Bulletin 2083-D, scale 1:126,720.

Gettings, M.E., 2002, An interpretation of the 1996 aeromagnet-ic data for the Santa Cruz basin, Tumacacori Mountains, Santa Rita Mountains, and Patagonia Mountains, south-central Arizona: U.S. Geological Survey, Open-File Report OF-2002-99, scale 1:175,000.

Graybeal, F.T. and four others, 2015, Geologic Map of the Pata-gonia Mountains, Santa Cruz County, Arizona. US Geological Survey, OFR-2015-1023

Gutierrez, John, 1996, Mineral resources and resource potential of Coronado National Forest - salable minerals: U.S. Geologi-cal Survey, Bulletin 2083-I, scale 1:126,720.

Hauser, B.B., 1992, Map of industrial mineral occurrences in the National Forests of Arizona: U.S. Geological Survey, Open-File Report OF-92-687, scale 1:500,000.

Houser, B.B., Gettings, M.E., Bultman, M.W., Gray, Floyd, Caroth-ers, K.R., and Hirschberg, D.M., 2000, Field trip guide to selected studies of the Southwest Mineral and Environmental Investigations Project in southeastern Arizona: U.S. Geological Survey, Open-File Report OF-99-544, scale 1:500,000.

Hyndman, Paul, and Campbell, H.W., 1999, Digital mining claim density map for Federal lands in Arizona: 1996: U.S. Geologi-cal Survey, Open-File Report OF-99-406, scale 1:100,000.

Lindsey, D.A., and Van Gosen, B.S., 2010, Processes of terrace formation on the piedmont of the Santa Cruz River Valley during Quaternary time, Green Valley-Tubac area, southeast-ern Arizona: U.S. Geological Survey, Scientific Investigations Report SIR-2010-5028, scale 1:200,000.

Lipman, P.W., and Sawyer, D.A., 1985, Mesozoic ash-flow caldera fragments in southeastern Arizona and their relation to por-phyry copper deposits [southern Sierrita Mts and southwest Santa Rita Mts]: Geological Society of America, Geology v. 13, n. 9, scale 1:278,000.

Moore, R.T., Jones, W.C., and Peterson, J.W., 1974, Maps show-ing nonmetallic mineral deposits in the Tucson area, Arizona: U.S. Geological Survey, Miscellaneous Investigations Series Map I-844-J, scale 1:250,000.

Nowlan, G.A., 1996, Geochemistry of Coronado National Forest: U.S. Geological Survey, Bulletin 2083-C, scale 1:126,720.

Peterson, J.A., 1990, Preliminary mineral resource assessment of the Tucson and Nogales 1 degree by 2 degree quadrangles, Arizona: U.S. Geological Survey, Open-File Report OF-90-276, scale 1:250,000.

Peterson, J.A., Berquist, J.R., Reynolds, S.J., and Page-Nedell, S.S., 2003, Geologic map of the Tucson and Nogales quad-rangles (Arizona, scale 1:250,000): a digital database: U.S. Geological Survey, Open-File Report OF-2001-275, scale 1:250,000.

Phillips, J.D., 2002, Processing and interpretation of aeromag-netic data for the Santa Cruz basin -- Patagonia Mountains area, south-central Arizona: U.S. Geological Survey, Open-File Report OF-2002-98, scale 1:220,000.

Ransome, F.L., 1922, Ore deposits of the Sierrita Mountains, Pima County, Arizona: U.S. Geological Survey, Bulletin 725, scale 1:600,000.

Riggs, N.R., and Haxel, G.B., 1990, The Early to Middle Jurassic magmatic arc in southern Arizona: Plutons to sand dunes: Arizona Geological Survey, Special Paper 7, scale 1:200,000.

Rystrom, V.L., Finn, C.A., and King, T.V.V., 2002, Geologic inter-pretation of aeromagnetic maps in the Santa Cruz basin - Pa-tagonia Mountains area, south-central Arizona: U.S. Geologi-cal Survey, Open-File Report OF-2002-100, scale 1:250,000.

Shankar, Vivek, 2009, Texture-based automated lithological classification using aeromagnetic anomaly images [Patagonia study area, Santa Cruz County, Arizona]: U.S. Geological Sur-vey, Open-File Report OF-2009-1206, scale 1:125,000.

Stipp, T.F., Haigler, L.B., Alto, B.R., and Sutherland, H.L., 1967, Reported occurrences of selected minerals in Arizona: U.S. Geological Survey, Mineral Investigations Resources Map MR-46, scale 1:500,000.

U.S. Geological Survey, 1973, Map showing potential for copper deposits in the eastern three-quarters of the Nogales 2 degrees quadrangle, Tucson area, Arizona: U.S. Geological Survey, Miscellaneous Investigations Series Map I-844-G, scale 1:250,000