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Copperin NewMexico

by VirginiaT. McLemore,New Mexico Bureau of Mines and Mineral Resources,801 Leroy Place,Socorro, NM 87801-4796

Abstract

Copper has been produced in New 82X X . ^29 Mexico since prehistoric times, but actual a ,"t33 ! production recordswere not kept until 1804. r 87Xi>21 From 1804to 1994,nearly 8.4million tons of r.. '. x 79 ,r approximate- 'r' '. were produced, worth / ly $10 billion. Three districts account for 93% of the total copper production (Santa Rita, Burro Mountains, Fierro-Hanover). Copper in New Mexico is found in 13 types a 'lt) i of deposits; the most important are Por- '.,1, phyry copper and Laramide skarn deposits. .t ir Today, three mines are in production with a copper as the primary product: Chino, Recoverable re- o10 i TVrone. and Continental. r serves at Santa Rita are reported as 315.4 riitr:rirl ti I I million tons of concentrator grading I .illir i : 477 0.67ohCrand720.5million tonsof leachore grading 0.24% Cu. Recoverablereserves at Tyrone (Burro Mountains district) are esti- 465 - mated as 230 2 million tons of leach ore x85 i 12 grading 0.35% Cu Cobre Mining Co. 24 x86 i 1r {53 reports minable reservesat the Continental lI ri ,, ' mine (Fierro-Hanover district) of more than ii ir:,t ti-r t35 i i a16 10 million tons of 0.92% Cu. Minable re- ""' i ^31 servesat the Copper Flat porphyry copper ' 467 AJZ..a deoosit are estimated as 60 million tons of _ -*-- _-- t_ O+Z% Cu and 0.0L2"/" Mo. Additional deposits in these and other areasare likely a75 to be discovered,especially in districts with 84x. potential for porphyry copper deposits and ' ^:rq 468 copPer sKams. r40: I .t , 3/L r -- - *1: 'i 3B i _^^ Introduction its, : 7o) i Copper has been produced in New I.t Mexico since prehistoric times, but actual production records were not kept until 1804.From 1804to l994nearly 8.4 million o+ 50mi 0 50km Alsoin this issue ' Volcanic-epithermalvein deposits e Rio Granderift baritejluorite-(copper/ NMGS 1996fall conference p.36 ' Supergenecopper- () deposits silver)deposits NM MineralMuseum news p.37 r ^ Great Plainsmargin (alkalic-related) deposits Carbonate-hostedlead- (copper/silveO Upcomingmeetings p.37 replacementdeposits t MississippiValleytype deposits VillanuevaState Park p.38 r silver-() a Carbonate-hosted Sedimentary-copperdeposits replacementdeposits NMGS 1996spring * Laramidevein deoosits meetingabstracts X Veinand replacementdeposits in Precambrian P.42 * Laramidelead-zinc and copperskarn rocKs Service/News p.59 deposits . Precambrianvolcanogenic massive- o Porphyry-copper(gold, ) deDosits deposits Comingsoon La Bajadauranium mine FIGURE 1-Mining districts with reported copper production. Symbols refer to type of deposit; Stratigraphyof Tr-4 some districts have more than one type, but only the predominant type is shown. Not all districts PecosRiver valley vertebrates with copper occurrences are shown. tons of copper were produced in the state, Today copper is widely used in the elec- which are on file at the New Mexico amounting to approximately $10 billion trical and communications industries, Bureau of Mines and Mineral Resources. (Table 1). The major copper districts are building construction, consumer prod- However, some of these production fig- shown in Fig. 1. Three districts accountfor ucts, machinery, transportation, and mili- ures are subjectto change,as new data are 93"/"of the reported copper production in tary applications.New Mexico has ranked obtained. Mining and, especially,produc- New Mexico (Santa Rita, Burro Moun- third in the U. S. in copper production tion statisticsare generally poorly record- tains, Fierro-Hanover; Table2). since \992 (Energy,Minerals and Natural ed, particularly in the earliest times, and Resources Department, 1994). Approxi- many of those early records are conflict- mately 2,540 people were employed by i.g. TABLE1-Estimated copper production from the industry New Mexico, 7804-7994(from Lindgren et a1., copper in New Mexico in 1910;Anderson,1957;U. S. GeologicalSurvey, 1994wlth a payroll of more than 988 mil- History of copperproduction 1902-7927;U. S Bureau of Mines, 7927-1994: lion (New Mexico Energy, Minerals and in New Mexico Energy, Minerals and Natural Resources Natural Resources Department, press Department, 1994). release,May 24,7995). The first use of copper was by American The purpose of this paper is to presenta Indians, for ornaments and tools. Later, Years of Copper Value brief summary of the copper resourcesin Francisco Vasques de Coronado led a Production (short tons) ($) New Mexico. Best available information Spanish expedition into New Mexico in on copper production from the state since 1540 looking for gold (jones, 1904). 1804-1880 15,003 6,001,,205 1804 is summarized in Table 1 and by Instead Coronado found turquoise; early 1881-1903 23,554 5,831,500 major district in Table2. Theseproduction Spanishmining for turquoise-andcopper 190+-1920 ??R lrC 138,857,559 figures were obtained from a variety of in New Mexico occurred in Cerrillos and 7927-1940 607,346 151,850,186 published and unpublished sources, in- Old Placers districts in Santa Fe Countv. 1947-7960 t,3t6,268 613,905,615 cluding the U. S. Geological Survey Placitas in 7961.-1980 2,686,467 Sandoval and Bernalillb 3,072,497,160 (1902-1927),the 1987-7994 3,379,866 U. S. Bureau of Mines Counties, and SantaRita near Silver City. 6,002,737,421 (1927-1994) Est. total Mineral Yearbooks,and vari- One of the first known copper opeia- ous 7804-7994 8,360,929 9,992,080,646 company annual reports, most of tions was at SantaRita. In 1798an Apache

NII N / O TABLE 2-Malor copper districts inNew Mexico (compiled by V. T. Mclemore from U.S.Geological Survey, 7902-7927;U.S. Bureau of Mines, 7927-7994;and various published and unoublis'hed ll\ew A exleo sources,including company annual reports). District number refersto Fig. l. GEOLOGY District County Estimated copper Type(s) of Major commodities . Scienceand Service (lbs) production deposit rssN o196-948X Volume18, No.2, 1. SantaRita (Chino) Grant 9,080,000,000 Porphyry copper Cu (Ag, Au, Mo) May 1996 2. Burro Mountains Grant 5,240,000,000 Porphyry copper/ Cu (Ag, Au) Editor: Carol A. Hjellming (Tyrone) Laramide vein EDITORIAL BOARD Steve M. Cather, NMBMMR, Chairman 3.Fierro-Hanover Gralt 1,250,000,000 Laramideskam, C:u,Zn,Pb Thomas Giordano, NMSU Laurel B. Goodwin, N prophyry copper MIMT Spencer- G. Lucas, NMMNHS 4. Lordsburg Hidalgo 229,577,000 Laramide vein Ctt, Au, Ag,Pb,Zn Fn^k I. Pazzaglia, IJNM 5. Bayard Grant 110,000,000 Laramide vein Zn,Cu,Ag,Pb Published quarierly by New Mexico Bureau of Mines and 6. Pinos Altos Grant 59,500,000 Laramide skarry Cu,Zn, Pb,Ag (Au) Mineral Resources Laramide vein a division of New Mexico L$titute of Mining and Technology 7. Willow Creek San Miguel 18,687,426 Volcanogenic mas- Zn,Pb, Cu, Ag BOARD OF REGENTS sive sulfide Ex-Officio 8. Hillsboro Sierra Gary Johnsory Gozernor of Nm Mexico 17,000,000 Laramide vein, Cu, Au (Ag, Pb) Alan Moigm, Supuintendent of Public Instruction porphyty copper Appointed Steve Torrc, Presid6t , 1991.-7997, Albuquerque 9. New Placers Santa Fe 17,000,000 Great Plains margin Cu, Au, Ag(Pb,Zn) Delilah A. Yega, Student Member, SecretaryEleasurer, 1995-1997, Socono 10.Pastura Guadalupe 1.3,578,21,4 Sedimentary copper Cu (Ag, Pb) Diane D. Denish, "1992-1997,Albuquerque 11.Magdalena Socoro 12,000,000 Carbonate-hosted Zn,Pb,C:u(Ag) J. Michael Kelly, 1992-7997,Roswell Charles A. Zinnerly, 199]-1997, Socorro Pb-Zn replacement New Mexico Institute of Mining and Technology 12.Gallinas Lincoln 8,000,000 Great Plains margin, Cu,Pb (Ag,Zn) President. ... DanielH. L6pez sedimentary copper New Mexico Bureau of Mines md Mineral Resources Director and StateGeologist...... Charles E. Chapin 13.Nacimiento Sandoval 7,561,,567 Sedimentary copper Cu (Ag) Subsuiptions: Issued quarterly, February, May, 14. Orogrande Otero 5,700,000 Great Plains Au, Cu (Ag,Pb,Zn) August, November; subscription price $6.00/calen- margin skam qar yeal publication 15. Organ Mountains Dofla Ana 4,636,000 Carbonate-hosted Editorial Matter: Articles submitted for Pb,Zn,Cu, Ag (Au) should be h the editor's hands a mhinium of five Pb-Zn replacement (5) months before date of publication (February 16. Lincoln 4,201,474 May, Augusf or November) md should be no |icarilla Great Plains margin Au,Ag, Cu longer than 20 q?ewritten, double-spaced pages. 17. Chloride Sierra 3,060,000 Volcanic epithermal Ag, Pb (Au, Cu) All scientific papers will be reviewed by at least two people in the appropriate field of study. Address 18.Mogollon Catron 1,500,000 Volcanic epithermal Ag, Au, Pb, Cu hquiries to Carol A. Hjellming, Editor of Neru Mexico New Mexico 19.Apache No. 2 Hidalgo Ceology, Bureau of Mires and 1,300,000 Carbonate-hosted Ag (Pb, Zn, Ctt) Mineral Resources. Socorro, New Mexico 87801- Pb-Zn replacement 4796. Publishedas public domain, thereJore 20, SteepleRock Grant 1,200,000 Volcanic rErod.uciblewithout epithermal Ag,Au, Pb,Zn,Cu permission.Sourrc crel.it reauested, Estimated total Circulation: L,000 New Mexico aIl 16,720,000,000 all Printer: Univercity of New Mexico Printing Services

May 1996 New Mexico Geology Indian led Col. Manuel Carrasco, a niques were developed, and copper Phelps Dodge Corp. began development Spanish officer, to these copper deposits, became an important commodity. Times of the Tyrone open-pit mine in the Burro and by 1804 copper was being mined at were exciting for the miner in the late Mountains district. In1974 Phelps Dodge Santa Rita and transported by mule to 1800s metal including copper/ Corp. built the Plavas smelter in the _as prices, Mexico Citv. Actual production records soareo. Animas Valley in Uidatgo County; the are lacking, but Chrisiiansen (1974) esti- In 1904 Daniel C. Jackling opened the smelter is still operating. In January 1992 mates 200 mule trains were sent annually, first large, open-pit mine to produce low- the Tyrone mill closed and the Tyrone amounting to approximately 6,000,000 lbs grade copper ore (less than 2"h Cu) by mine became a mine-for-leach operation, (3,000 short tons) of copper per year. bulk-mining methods at Bingham Can- the first in the state. Cobre Mining Lindgren et al. (1910) estimates total pro- yon, Utah. At the same time, John M. Sully Company, Inc. resumed production at the duction from 1804 to 1879 as 15,000 short arrived at Santa Rita and recognized the Continental mines in luly 1993. tons of copper. Mining at Santa Rita di- similarity of ore at Santa Rita to that In the 1980s solvent extraction-elec- minished after 1809 as a result of increas- mined at Bingham Canyon. Sully acquired trowinning (SX-EW) technology was ing costs, difficult transportation, Indian the mineralized area and attempted to developed that enabledeconomic recov- uprisings, declining copper demands in obtain backers (Sully, 1908). Finally, in ery of high-purity copper from very low Mexico, and finally the Mexican Revolu- 1909 he obtained the financial backing, grade copper deposits.TWo SX-EW plants tion in 1810. The records are conflicting as and in 1910 production began. The first currently operatein New Mexico: Tyrone, to who owned and operated the mines concentrator was erected at Hurley in begun in April 1984,and Chino, begun in after 1809, and the mines finally closed in 1911; flotation concentration was added in August 1988.Solvent extraction removes 1834. They were still inactive when 1914. The facilities at Hurley have been copper from a pregnant leach solution, by General Kearney and the U. S. Army visit- modernized several times since. Smelter mixing it with an organic extractant,into a ed the area in 1846 (Jones, 1904; Milbauer, operations at Hurley continue today as solution of sulfuric acid and copper sul- 1982). does mining at Santa Rita. In 1909 Phelps fate. The resulting electrolyte solution is In 1848 New Mexico Territory became Dodge Corp. purchased the mines and pumped into the electrowinning tanks. part of the United States and gold and sil- concentrator at Tyrone in the Burro Copper is plated onto cathodes. A very ver mining began in earnest. Numerous Mountains district. high purity copper is produced in this districts were discovered and mined for New Mexico became a state in 1912 and manner as opposed to concentratiorubut precious metals in the 1800s (North and in \91.4 World War I began. Metal prices no gold, silver, or molybdenum can be Mclemore, 1986; Mclemore, in press a); and production increased as metals were recovered. SX-EW enables leaching of copper was recovered wherever it was need-ed for the war effort. In 1918 World very low grade copper (as low as possible. Copper mining at the Hanover War I ended and was followed by a 0.1% Cu) that contain easily leached cop- mine in the Fierro-Hanover district depression that closed many mines, per minerals such as ,chrysocol- occurred 1858-1861 (Hillesland et al., including the underground mines at la, and copper carbonates. 1995). However, most mining in the state Tyrone. Today three mines are in production ceased in 7862 with the invasion of New New selective-flotation metallurgical with copper as the primary product: Santa Mexico by the Confederate forces. techniques were developed in the 1920s Rita, Tyrone,and Continental.Pinos Altos, The end of the Civil War brought that improved recoverv of massive lead operated by Cyprus Pinos Altos Corp., tremendous change to mining in New and zinc sulfide ore. In 1927 oroduction closedin I995.In termsof copperproduc- Mexico. Settlers and prospectors fled the began at the Pecosvolcanogenic massive- tion by state in the United States, New war-torn East to start new lives in the sulfide deposit in the Willow Creek dis- Mexico ranked 2nd from 1984to 1991and West. Prospectors from the California gold trict in San Miguel County by the 3rd from 1992to 1994.In 1994,of the 42 fields moved eastward into New Mexico American Metal Co. (now AMAX producing copper mines in the United as the California placers were exhausted Resource Conservation Co.). This was the States, Chino ranked 4th, Tyrone 10th, or claimed. Soldieis were sent to eliminate largest lead- and zinc-producing mine in Continental 16th, and Pinos Altos 20th interference by Indians and later became the state at the time; copper was recovered (Daniel Edelstein, U.S. Bureau of Mines, prospectors themselves. Exploration as a byproduct. Significant production oral comm. October 77, t995). A small throughout New Mexico for gold and sil- continued through 1939 when the mine amount of copper, as silica flux, was ver deposits soared. Southwest New closed. Reprocessing of the dumps reported from the Lordsburg mine in the Mexico was one of the last areas in the occurred 1943-1944. Lordsburg district, which ranked 37th in United States to be rid of the threat of World War II saw an increasein copper 1994. Indian attacks, and many mining districts production, because the metal was needed there were not discovered until for war materials (Table 1), and was fol- Types of deposits 1890-1900. lowed by a depression. Copper prices The Federal Mining Act of 1866 estab- gradually increased and copper produc- Copper is found in 13 types of deposits lished rules and regulations governing tion from the porphyry copper and skarn in the state (Table 3). Economically, the prospecting and mining with provisions deposits steadily increased, with a few most important tlpe is the porphyry cop- for obtaining private ownership of federal slumps from year to year caused by price per deposit. The classification used in this Iand containing valuable mineral resour- fluctuations and labor disputes. Extensive report is described by North and ces. The act was subsequently amended in exploration worldwide for porphyry cop- Mclemore (1986,1988) and Mclemore (in 1870 and 1872 and in the years since. The per deposits occurred from about 1955 to press a). mining act further encouraged mining the early 1980s and resulted in discovery and prospecting in the state, and the min- of several deposits in New Mexico. In Volcanic-epithermal vein deposits ing boom of 1870-1890 began. Many dis- 1962-1964 the U. S. Smelting, Refining, tricts began production as the Indian and Mining Co. discovered the large Volcanic-epithermal vein deposits in threat was subdued. Copper and tur- deposits now being mined at the New Mexico include deposits that were quoise were found in the Burro Moun- Continental mines by Cobre Mining formed by ascendingwaters at shallow to tains in 1871 (Kolessar, 1982). The tele- Company, Inc. (Hillesland et al., 1995). moderate depths (<1,500 m) and low to graph and then the railroad improved Production at the Continental mines moderate temperatures (50'-300"C) and conditions in the state as mining contin- began in 1967 and ceased in 1982 as a that are typically associated with intrusive ued to flourish. New metallurgical tech- result of declining copper prices. In 1967 and/or volcanic rocks in structurally com-

New Mexico Geology May 1995 TABLE 3-Classification of copper deposits of New Mexico arranged by perceived age of the at areas with a change in strike and/or *, deposits (North and Mclemore, 1986, 1988; Mclemore, in press a). deposits where copper is a dip. Typical deposits are a few hundred major commodity; ?, uncertainty in age. U.S. Geological Survey classification from Cox and Singer thousand tons or less with variable copper (1986). grades (0.1-20%). These deposits provide excellent silica flux material for local Classification (this report) Perceived age USGS classification smelters and will be in continued demand as long as such undesirable elements as Volcanic-epithermal vein deposits Eocene-Pliocene 25b,cd,e fluorine and bismuth are low. copper-uranium (silver) Miocene-Pliocene? none deposits Supergene copper-uranium Great Plains margin (alkaline-related) Eocene-Miocene 22b,c,21a,18b,cd,39a (silver) deposits deposits Rio Grande rift barite-fluorite-galena Paleozoic?-early Tertiary 32a,79a TWo deposits in New Mexico, La Bajada (copper, silver) deposits (formerly and Jeter (Ladron Mountains), are classi- sedimentary hydrothermal deposits) fied as supergene copper-uranium (silver) Carbonate-hosted lead-zinc (copper, Eocene-Oligocene 79a deposits. These deposits were formed at silver) replacement deposits low temperatures, near the surface, and Carbonate-hosted silver-manganese Paleocene-Oligocene? 19b along Tertiary faults. Copper, silver, (iead) replacement deposits molybdenum, and uranium are found in production from La *Laramide lead-zinc and copper Late -Eocene 18b,c,d both deposits. Copper skarn deposits Bajada consisted of 5,345 pounds Cu; ura- nium, vanadium, and silver were also pro- *Laramide vein deposits Late Cretaceous-Eocene 22c duced (Mclemore and North, 1984). Only (poll'rnetallic veins) uranium and vanadium were produced "Porphyry copper (gold, Late Cretaceous-Eocene 21a,b from the ]eter mine (Chamberlin et al., molybdenum) deposits 1982). Copper occurs in variable amounts Mississippi Valley-type (MVT) deposits ?-Miocene 32a in both deposits. It is unlikely that these (here restricted to Permian Basin) small, Iow-grade deposits would be *Sedimentary copper deposits Pennsylvanian- 30b mined conventionally for their copper Vein and replacement deposits Precambrian-Tertiary 22b,c,26b contents. (here restricted to Permian Basin) *Precambrian volcanogenic massive- Precambrian 24ab,28a Great Plains margin deposits sulfide deposits (VMS) Some of the state's largest gold deposits occur along a north-south belt roughly TABLE 4-Volcanic-epithermal vein deposits with reported copper production in New Mexico. coinciding with the Great Plains physio- Number refers to Fig. 1. graphic margin with the Basin and Range (Rio Grande rift) and Rocky Mountains District, County Year of Period of reported Estimated copper physiographic provinces. These deposits discovery production production (lbs) have similar characteristics that, when compared with their tectonic setting, 17. Chloride, Sierra r879 7934-1992 3,060,000 define a class of ore deposits referred to as 18. Mogollon, Catron t875 1875-1988 1,500,000 Great Plains margin deposits, also known 20. Steeple Rock, Grant 1860 1880-1993 1,200,000 as alkaline-related gold deposits (North 21. Red River-Rio Hondo, Taos t826 7902-1956 77,000 and Mclemore, 1986, 1988; Mclemore, in 22. Gillespie, Hidalgo 1880 1880-1950 15,000 press c). Copper occurs in most districts, 23. Kimball, Hidalgo t875 7875-7953 12,000 and four have yielded significant produc- 24. Hop Canyon, Socorro 1880 1973-7947 7,000 tion (Fig. 1; Table 5): New Placers, 25. Cochiti, Sandoval 1880 1894-1983 2,500 Gallinas, Orogrande, and jicarilla. 26. Fremont, Hidalgo 1860 1880-1951 2,000 The Great Plains margin deposits con- 27. Cora Miller, Grant 1880 7940-1941, withheld tain both precious and base metals, but precious metals, especially gold, are typi- cally high. These deposits consist of seven plex areas. The characteristics of these of these deposits are diverse and typically styles of mineralization: (1) poly'rnetallic, deposits and a model for their formation varv from one deDosit to another. District epithermal to mesothermal veins, (2) are outlined by Buchanan (1981). The vol- zoning is also diverse, and in some dis- gold-bearing breccia pipes and quariz canic-epithermal vein deposits of New tricts precious metals occur in the upper veins, (3) porphyry copper-gold and por- Mexico formed usually in Oligocene to levels and grade into base metals at depth phyry gold, (4) copper-lead-zinc skarns or Miocene volcanic rocks, commonly adja- (Buchanan, 1981; Mclemorc, L994a, in carbonate-hosted replacements, (5) cent to calderas, but typically formed press b). Common ore minerals include skarns and replacement bodies, (6) placer much later than the caldera (Elston, !994; auriferous , native gold, acanthite, gold, and (7) rare-earth element (REE)-flu- Rytuba, 1981; Mclemore, 1994a) although , , argentiferous gale- orite eDithermal veins and breccias. other volcanic settings, such as silicic na, native silver, and . , Alkaline igneous rocks, typically domes and andesitic stratovolcanoes, are , and pyrite are common gangue Oligocene, are found in most districts, but not uncommon for these deposits. Typical minerals. Copper minerals occur in most mineralization is usually associated with volcanic-epithermal vein deposits in the districts (Fig. 1), but only three districts silica-saturated (monzonite) or oversafu- state occur as siliceous vein fillings, brec- have yielded significant copper produc- rated (quartz monzonite) rocks. The veins cia pipes, disseminations, and replace- tion (Table 4): Chloride, Mogollon, and have high gold to base-metal ratios ment deposits along faults and fractures. Steeple Rock. Ore shoots, less than 2 m (Thompson, 1991a; Mclemore, in press c). The mineralogy and metal associations wide, form at the intersection of faults or Although porphyry gold deposits, such as

May 1996 Nezo Mexico Geology the Fort Knox deposit in Alaska, have sim- TABLE S--Creat Plains margin deposits with reported copper production in New Mexico. Number *, ilar mineralization and alteration styles as refers to Fig. 1. includes production from sedimentary copper deposits. Age dates are from porphyry copper deposits, the porphyry Atkinson (1961), Perhac (1970), Beane et al. (7975), Bloom (1975), Marvin and Dobson (1979), Scott et (1990), (1978), b), and Allen and Foord (199L). gold deposits differ in that they contain al. Bachman and Mehnert Thompson(199La, less than l"/" total , have a low Cu District, Countv Year of Period of reported Age of igneous Estimated copper to Au ratio, and have a typical metal asso- discovery production intrusives production (lbs) ciation of gold, bismuth, , and molybdenum (Hollister, 1992). Although 9. New Placers, Santa Fe 1839 t839-1968 47.7t3.9 17,000,000 porphyry copper deposits have been 12. Gallinas, Lincoln* 1885 t909-7954 30.7 8,000,000 pro- found in some districts, none have 14. Orogrande, Otero 1879 t879-1966 43.749.5 5,700,000 duced. (Al ka line-related porphyry copper 4)O1 474 16. Jicarilla, Lincoln 1850 7912-7957 39.2r1,.5 deposits are described separately in this 28. Elizabethtown-Ba1dy, 1866 7866-7968 29.1r7.4 329,237 report.) Most copper production in Great Colfax Plains margin deposits in New Mexico 29. Cerrillos, Santa Fe 1680 1879-1957 28.748.2 ))q ca\ has come from copper skarns and carbon- 30. Old Placers, Santa Fe 7828 1828-7986 2648.2 r,570 ate-hosted replacements. Only one alka- 31. White Oaks, Lincoln 1850 1850-1951 29.8-36.1 1,000 Iine-related skarn deoosit in New Mexico 32. Nogal-Bonito, Lincoln 7865 1868-1955 26.5-38.3 withheld has been extensively studied; the Lukas 33. Cimarroncito, Colfax 1896 1,896-7940 29.7t7.4 withheld Canyon copper-gold skarn in Old Placers district contains a resource of 6 million tons of 0.25% Cu and 0.03 oz/ton Au TABLE 6-Rio Grande rift deposits with reported copper production in New Mexico. Number refers *, (Maynard, 1995). Copper will be pro- to Fig. 1. districts with minor copper production from veins and replacements in Precambrian duced from these deposits only as a by- rocks. product of gold production. District. Countu Year of Period of Estimated copper discovery production production (lbs) Rio Grande rift barite-fluorite-galena deposits 34. Hot Springs, Sierra 1930 1930-1950 76,650 35. Hansonburg, Socorro t872 1937-1957 12,600 (silver, Barite-fluorite-galena copper) 36. Caballo Mountains, Sierra+ 1881 1,937-1957 2,800 deposits, formerly called sedimentary 37. Bear Canyon, Dofta Ana 1900 early 1900s <10,000 hydrothermal deposits (North and 38. Black Mountain, Dofla Ana* 1883 1883-1900s <10,000 Mclemore, 1986, 1988), are found 39. San Andrecito-Hembrillo, 1890s 7974-1930 <10,000 throughout New Mexico along the Rio Dofra Ana* Grande rift (Fig. 1; Table 6; Mclemore and 40. San Andres Canyon, Dofla Ana 1900 1900-7904 <10,000 Barker, 1985;Van Alsttne,1976; North and 41. Salinas Peak, Sierra 1930s 1935-7948 100 Mclemore, 1985; Mclemore and Lueth, 1995; Mclemore et al., 1996). These deposits are low-temperature, open-space fillings with local replacement and are not basin brines accumulated in local basins deposits include replacements in carbon- obviously associated with any magmatic and were heated by high heat flow, mag- ate rocks with little or no calc-silicate min- activity. Rio Grande rift deposits in New matic activity, or radiogenic heat from erals, minor skarns with few calc-silicate Mexico are predominantly barite-fluorite- Precambrian plutons. The warm convict- minerals, and minor veins. Skarn deposits galena vein and replacement deposits; ing waters leach ions from source rocks do occur in some districts, such as locally they may contain significant such as arkosic sediments, evaporites, Magdalena and Apache No. 2, but the amounts of silver, copper, and zinc (Table Precambrian rocks, and Precambrian min- skarn minerals are neither as abundant 6). eral deposits. In central New Mexico, nor mineralogically zoned as in the The deposits typically occur as veins, these basins are continental instead of Laramide skarns. The host rocks are pre- breccia cements, cavity fillings, and minor marine, as in the classic Mississippi Valley dominantly Paleozoic and Cretaceous car- replacement bodies in carbonate rocks area, and are associated with extensional bonate rocks and adjacent intrusive rocks. adjacent to or within Basin and Range- tectonics. The mineralized waters were Many deposits are structurally controlled related faults (i.e. Hansonburg, Salinas ejected along open spaces such as faults along extension-related fault, , Peak; Kottlowski and Steensma, 1979; and fractures. Precioitation occurred as a and contact zones. The localization of Smith, 1981;Mclemore, 1994b;Mclemore result of cooling of the fluids, decrease in many deposits is also stratigraphically et al., 1996). Previous workers have attrib- pressure, and/or mixing of the mineral- controlled. They are typically lead and uted these deposits to the Tertiary ized hydrothermal fluids with subsurface zinc dominant, with byproduct copper, (Allmendinger, 1975; Beane, 1974; Seager brines or meteoric water. silver, manganese, and gold. Galena and et a1.,1971).Most Rio Grande rift deposits It is unlikely that many of these depos- sphalerite are the predominant ore miner- in New Mexico are small, typically less its will be mined solely for their copper als with lesser amounts of chalcopyrite. than a few thousand tons of ore. Widths as content. Most of these deposits are also The deposits vary in size and grade, much as tens of feet occur and some too small to be exploited for barite, fluo- ranging from a few thousand tons to a few deposits can be traced along strike for sev- rite, or lead. hundred thousand tons and typically eral thousand feet. grading 5-30% combined lead and zinc; These deposits are similar to Carbonate-hosted lead-zinc the amount of copper varies (0.1-20%; Mississippi Valley-type (MVT) deposits replacement deposits Mclemore and Lueth, 1995). Fluid-inclu- and were formed by low-temperature sion data from five deposits indicate tem- basin brines that were ejected along frac- Carbonate-hosted lead-zinc replace- Deratures of formation between 147 and tures, faults, and during ment deoosits occur in southwesf New 367"C andlow to moderate salinities (<10 early diagenesis or later compaction of Mexico and were formed approximately eq. wt'k NaCl; Mclemore et a1.,1996). sedimentary basins (Hanor, 1979; Ohle, 50-20 Ma (Fig. 1, TableT; Mclemore et al., The association between carbonate- 1980; Hill, 1993).The formation waters or 1996; Mclemore and Lueth, 1995). The hosted lead-zinc replacement deposits

New Mexico Geology May 1996 TABLE 7-{arbonate-hosted lead-zinc replacement, carbonate-hosted silver-manganese replace- et al., 1986) and the Magdalena district ment, and Laramide skarn deposits in New Mexico with copper production. Number refers to Fig. (Socorro caldera, 32 Ma and Saw- mill-Magdalena caldera, 28.9 Ma; McIn- tosh et al., t990) provide additional evi- District, Countv Year of Period of Estimated copper Type(s) of dence supporting an epithermal origin of discovery production production (lbs) deposit the carbonate-hosted Pb-Zn replacement deposits in New Mexico (Armstrong et al., 3. Fierro-Hanover, Grant 1850 1890-present 1,250,000,000Laramide skam 1995; Renault et al., 1995). Many of the 6. Pinos Altos, Grant 1860 1,890-199s 59,500,000Laramide vein, deposits in New Mexico occur along the Laramide skarn ring-fracture zones of calderas (McLe- 1.1.Magdalena, Socorro 1866 1866-1977 12,000,000Carbonate-hosted more et al., 1996). These deposits are also Pb-Zn replacement similar to the chimney, manto, and pod 15. Organ Mountains, Dofla Ana 1830s 7849-7961. 4,636,000Carbonate-hosted carbonate-hosted Ag-Pb-Zn(Cu) deposits Pb-Zn replacement in northern Mexico (Megaw et al., 1988). 19. Apache No. 2, Hidalgo 1870s 1880-1956 1,300,000Carbonate-hosted Geochemical data suggest that the Mexico Pb-Zn replacement deposits were formed by mixing of vari- 42. Eureka, Grant t871 1880-1961 500,000 Laramide skarn able amounts of magmatic and meteoric fluids (Megaw et al., 1988), and a similar 43. Carpenter, Grant 1891 7897-7969 310,000Carbonate-hosted epithermal origin is reasonable for the Pb-Zn replacement New Mexico deposits. 44. ,Hidalgo 1877 1902-7957 130,000Laramide skarn, The carbonate-hosted Iead-zinc replace- Laramide vein ment deoosits in New Mexico are not a 45. Kingston, Sierra 1880 1880-1957 177,950Carbonate-hosted significant source of copper, but copper Mn-Ag replacemenf could be recovered as a byproduct of lead carbonate-hosted and zinc production. SX-EW is not Pb-Zn replacement amenable to carbonate ores because the 46.Lake Valley,Sierra 1878 1880-1957 100,000Carbonate-hosted carbonate consumes the acid required to Mn-Ag replacement; leach the copper. Future development of carbonate-hosted these deposits is dependent on zinc and Pb-Zn replacement lead production. 47.TierraBlanca, Sierra 1900s 1919-7955 92,784 Carbonate-hosted Mn-Ag replacement Carbonate-hosted silver-manganese 48. McGhee Peak,Hidalgo 7894 7894-1956 85,000 Carbonate-hosted replacement deposits Pb-Zn replacement, Laramide skarry Carbonate-hosted silver-manganese porphyry-copper (lead) replacement deposits occur in 49. Victorio, Luna 1870s 1880-1959 41,000 Carbonate-hosted southwest New Mexico (Fig. 1, Table 7) Pb-Zn replacement and were formed during the mid-Tertiary. 50. Cooke's Peak,Luna 1876 1876-1965 23,000 Carbonate-hosted The deposits contain predominantly silver Pb-Zn replacement and manganese and locally contain some copper. The Lake Valley and King- 51. Granite Gap, Hidalgo L897 7897-1955 20,400 Carbonate-hosted ston districts each have produced more Pb-Zn replacement than 100,000lbs of copper-(Table 7). 52. Chloride Flat, Grant 7871 1,873-7946 20,000 Carbonate-hosted The deposits are hosted by limestones Mn-Ag replacement and dolomitic limestones. The Percha 53. Water Canyory Socorro 1868 1905-1956 15,377 Carbonate-hosted Shale commonly acts as the uppermost, Pb-Zn replacement impermeable cap on mineralization. 54. Rincon, Hidalgo 1880 1,940-1,949 <10,000Carbonate-hosted Jasperiods are common to most deposits Pb-Zn replacement and also act as impermeable caps. The 55. Lone Mountairy Grant 187L 7877-1950 5,000 Carbonate-hosted deposits typically consist of native silver, Mn-Ag replacement cerussite, vanadinite, wulfenite, and 56. Florida Mountains, Luna 1.876 1880-1956 5,000 Carbonate-hosted smithsonite. , argentiferous gale- Pb-Zn replacement na, , , , sphalerite, and chalcopyrite are rare to 57. Hermosa, Sierra 1930 1879-1956 1,850 Carbonate-hosted in most districts. Although silver Mn-Ag replacement common and manganese are the predominant met- 58. Ties Hermanas,Luna 1881 7885-7957 550 Laramide vein, als, Iead, followed by copper, is next in Laramide skarn abundance in most districts (Mclemore et 59. Georgetown,Grant 1866 1866-7983 withheld Carbonate-hosted a1.,1996). Mn-Ag replacement The carbonate-hosted silver-manganese replacement deposits are fair exploration and igneous activity is uncertain. Poorly ting, and temperature to the volcanic- targets for small mining companies developed skarns are present in some dis- epithermal vein deposits in New Mexico because they tend to be high grade and tricts, suggesting magmatic fluids are (Mclemore et al., 1996); the main differ- small to medium size. The limestones are involved with ore fluids. Tertiary intru- ences between the two are the differences typically silicified and could, in local sive rocks with veins and/or dissemina- in host rock and mineralogy. Similarities areas, be used as siliceous flux material. tions of sulfides ranging from 50 to 20 Ma in texture, mineralogy, and temperature of Metallurgical problems in recovering sil- crop out in most districts. The carbonate- alteration and mineralization between ver from the manganiferous ores has ham- hosted lead-zinc replacement deposits are altered carbonate rocks pered production in the past, but new similar in form, texture, age, tectonic set- from the Valles caldera fl.12ll4a: Gardner recovery methods may offer better recov-

May 7996 New Mexico Geology eries in the future. Copper could be recov- Ag, and 0.024 oz/ton Au (Osterberg and these differences, these deposits are ered as a byproduct. Muller, 1994),but the mine closed in 1995. grouped together becauseof similar form, Cobre Mining Co. reports reserves at the associationwith Laramide intrusive rocks, Laramide skarn deposits Continental mine in the FierreHanover and perceived origin at moderate to high district of more than 10 million tons of temperaturesand moderate depths. Laramide skarn deposits in New 0.92% Cu (Hillesland et al., 1995). The Laramide veins may have potential for Mexico are contact-metasomatic deposits Chino mine in the Santa Rita district also siliceous flux. Veins in the Lordsburg dis- that formed in carbonate rocks adiac-entto contains large copper skarns, but reserves trict containing copper, gold, and silver Laramide calc-alkaline plutonic rocks are not separated from the porphyry cop- have been mined for silica flux. Past pro- (7543 lda; Fig. 1, Table 7; Mclemore and per deposits. Skarn deposits must be duction indicates that these deposits are Lueth, 1995). Three tlpes of Laramide processed by conventional technologies small to medium tonnage. skarns occur in southern New Mexico: because these carbonate ores are not copper (typically associated with por- amenable to SX-EW processing. Porphyry copper (molybdenum, gold) phyry copper deposits), lead-zinc (proxi- deposits mal and vein-type deposits), and iron Laramide vein deposits skarns. The largest copper skarns are in Porphyry copper (molybdenum, gold) the Santa Rita, Fierro-Hanover, and Pinos Vein deposits of Laramide age (7543 deposits are large, low-grade (<0.8% Cu) Altos districts. Laramide iron skarns are Ma) occur in a number of districts, the copper deposits of disseminated and found only in the FierreHanover district. most important of which are Lordsburg, stockwork veinlets of copper sulfides that District zoning is common in most Bayard, and Hillsboro (Fig. 1, Table 8); the are associatedwith porphyritic intrusions areas, with copper adjacent to the intru- Pinos Altos district also contains (Fig. 1, TabIe9; Lowell and Guilbert, 1970; sive rocks grading outwards to zinc-lead, Laramide vein deposits. The veins exhibit Lowell, 1974). Mineralization typically lead-zinc, lead-silver, and locally, lead-sil- different texture and mineralogy, but are occurs in and around prophyritically ver-manganese (Meinert, 1987; Mclemore similar in form and age. Host rocks vary altered dioritic to granitic plutons that are et a1.,1996). Copper skarns are typically from Precambrian to younger sedimenta- surrounded by concentric zones of intimately associated with plutons (e.g. ry and volcanic rocks. The veins were typ- hydrothermal alteration (Lowell and Santa Rita, Pinos Altos), whereas the lead- ically worked for both base and precious Guilbert, 1970).Supergene enrichment is zinc skarns are not alwavs directlv associ- metals and locally contain uranium, tung- important in many depositswhere oxidiz- ated with igneous rocks. sten, and . Mineralogy and ing meteoric waters dissolve primary The Laramide skarns in New Mexico metal associations are diverse. Despite minerals that are then redeposited under formed from variable but higher tempera- ture and more saline fluids comoared to other carbonate-hosted depositi in the state (Mclemore and Lueth, 1995). Most TABLE 8-Laramide vein depositsin New Mexico with copper production. Number refersto Fig. 1. deposits probably formed from mixing of meteoric and magmatic fluids (Abramson, District, County Year of Period of reported Estimated copper (lbs) 1981; Ahmad and Rose, 1980;Lueth,7984; discovery production production Turner, 1990; Turner and Bowman,1993). 1885-1994 229,577,000 The potential for discovering additional 4. Lordsburg, Hidalgo 1870 1858 7902-1969 110,000,000 skarns in these districts is excellent, but 5. Bayard, Grant 8. Hillsboro, Sierra 7877 7877-1987 10,000,000 development of these deposits will 60. White Signal, Grant 1880 1880-1968 26,000 depend on the copper market. Cyprus 61. Gold Hill, Grant 1884 7911,-1941 6,845 Pinos Altos Corp. reports reserves at the 62. Black Hawk, Grant 1881 1881-1960 3,000 Pinos Altos mine of more than one million 63. Telegraph, Grant 1881 1938-1951 7,700 tons of 4.96% Cu,2.54% Zn, 3.5 oz/ton 64. Fleming, Grant 7882 7882-1948 450

TABLE 9-Porphyry copper deposits in New Mexico. Mineralized zones have been found in the Organ Mountains district that are indicative of a por- *, phyry copper deposit, but no reserves have been delineated. Number refers to Fig. 1. References for age determinations are in text. reported reserves are recoverable copper reserves; **, skarn or carbonate-hosted replacement deposits also present.

District, Countv Year of Period of Age (Ma) Estimated copper Reported estimated discovery production production (lbs) leserves ok 1. Santa Rita (Chino), Grant** 1800 1804- 57.3-60.4 9,080,000,000 315.4million tons 0.67 Cu (concentrator), presenr 720.5million tons of 0.24'/.Cu (leachable)* 2. Burro Mountains (Tyrone), 1877 1871.- 52.8-56.6 5,240,000,000 230.2million tons 0.35%Cu (leachable)* Grant present 8. Hillsboro (Copper Flat), Sierra 7970s 7982 75.7 z000,ooo 60 million tons 0.42"/"Cu,0.012%Mo(minable) 3. Fierro-Hanover 1970s none 57.55 none 80 million tons 0.38%Cu (geologicreserves) (Hanover-Hermosa Mountain), Grant** 48. McGhee Peak, Hidalgo*+ 1970s none none unknown----exploration underway 29. Cerrillos, Santa Fe** 1959 none 28.748.2 none 10 million tons of 0.30%Cu (contained) 30. OId Placers 1970s none 29.9 none none (Cunningham Gulch)** 14. Orogrande, Otero** 1970s none 43.749.5 none 335,000tons of 0.7%CuO (contained) 15. Organ Mountains (?), 1.980s none 34.4 none unknown Dofla Ana**

New Mexico Ceology May 1996 reducing conditions (Titley and Marozas, from 66.3 to 60.4 Ma (K-Ar, McDowell, from 72.2+2.1, to 58.6+2.0 Ma (K-Ar, 1995). Supergene deposits typically form 1971; recalculatedusing new decay con- McDowell, 197'1.;rccalculated using new enriched blankets of chalcocite and other stants),but Phelps Dodge Corp. data sug- decay constants); a granodiorite porphyry copper minerals that are overlain by a gests the age of the stock is 56.5-58.2Ma sample collected from the Continental pit leached cap of variable thickness. One or (Wunder and tujillo, 1987).Total produc- was dated as 57.55+0.07 Ma (aoAr/3eAr, more periods of supergene enrichment are tion from 1911to 1993is estimatedas 4.54 Mclemore et a1., 1995). Drilling in the common to the larger porphyry copper million tons of copper from 500 million 1970s and 1990s has delineated 80 million deposits (Cook, 1994; Titley and Marozas, tons of ore (Long, 1995).Reserves (recov- tons of geologic reserves of 0.38% Cu at 1995;DuHamel et al., 1995). erable copper) are reported as 315.4 mil- Flanover Mountain, northeast of the Porphyry copper deposits are the most Iion tons of ore grading0.67%Cu (Phelps Continental mine (Hillesland et al., 1995). important tJpe of copper deposit in the Dodge Co.,1,995). The deposit at Hermosa Mountain, south- world. The Tyrone (Burro Mountains dis- The Tyrone west of the Continental mine, has not been trict) and Chino (Santa Rita district) mines occurs within a quartz-monzonite laccol- defined. (Table 9) were the 3rd and 5th largest cop- ith and adjacent Proterozoic rocks During drilling in the early 1970s and per mines in the United States in 1990 (Kolessar, 1982). The age of the Tyrone 1990s a porphyry copper deposit was flolly and Edelstein, 1992). In 1994, the stockis 52.8t1.2to 56.6+1.6Ma (K-Ar,R. I. found at 100 ft deep in the northwest part Chino mine was the 4th and the Tyrone Stegen,Phelps Dodge Mining Co., written of the McGhee Peak district (Mclemore et mine was the 10th largest copper mines in comm. October 3, 1994;DuHamel et a1., al., 1996). Carbonate-hosted lead-zinc the United States (Daniel Edelstein, U. S. 1995).At least three cyclesof supergene replacement and Laramide skarn deposits Bureau of Mines, oral comm. October 17, enrichment have concentrated the ore occur in the district and yielded 12 million 1995). during the Eocene (approximately 3945 lbs Pb, 10 million lbs Zn, and 85,000 Only the known deposits in New Ma), early Miocene (approximately 16-19 pounds Cu (Mclemore et al., 1996). Mexico that have produced, are under Ma), and late Miocene (approximately Cyprus Minerals Corp. has filed claims in permitting, and/or have reported re- 8-10 Ma; Cook, 1994; DuHamel et al., secs. 30 and 31 T24S R21W and plans to serves are included as porphyry copper 1995).Several ore bodies, sometimescon- continue exploration drilling. Quartz- deposits in this report. The copper skarn sidered separate porphyry copper depo- pyrite and argillic alteration occurs in deposits associated with Laramide por- sits, have been found. Approximately 300 most drill holes. No other information phyry deposits are classified as Laramide million tons of ore grading0.81% Cu were describing the porphyry copper deposit is skarns. There are eight known porphyny processedby the concentrator from 1969 available. copper deposits in New Mexico: Chino in to 1992.Approximately 425million tons of Aporphyry copper deposit was discov- the Santa Rita district; Tyrone in the Burro ore grading 0.35%Cu have been leached ered in the Cerrillos district at Bear Creek Mountains district; Copper Flat in the (R. j. Stegen,Phelps Dodge Mining Co., in 1959-19 60 (Wargo, 1964; Akright, 1979; Hillsboro district; Hanover-Hermosa written comm. October 3, 7994).Reserves Giles, 1995). Thin veins and dissemina- Mountain in the Fierro-Hanover district; (recoverablecopper) are estimated as 230 tions of copper sulfides occur in a mon- McGhee Peak district in the Pelloncillo million tons of ore grading 0.35% Cu zonite porphyry stock; there is no super- Mountains; Cerrillos district; Cunning- (PhelpsDodge Co., 1995). gene chalcocite blanket (Giles, 1995). The ham Gulch in the Old Placers district; and The Copper Flat deposit in the Hills- leach cap is 100-400 ft thick (Giles, 1995). the Orogrande district (Table 9). Most are boro district, discovered in 1975,consists Latites and monzonites range from Laramide in age (Late Cretaceous-Eo- of copper, gold, molybdenum, and silver 28.9t1.0 to 48.2t3.2 Ma (Bachman and cene) and calc-alkaline in composition. disseminatedin a ouartz-monzonite stock Mehnert, 1978; Aronson and Lee, 1986). In The Cerrillos, Cunningham Culch, and and in quartz veins (Dunn, 1982, 1984). 1976 Occidental Corp. estimated that the Orogrande deposits are alkaline-related, Unlike the SantaRita and Tyrone deposits, deposit contained 10 million tons of ore Oligocene-Miocene Great Plains margin there is no supergeneenrichment zone at grading 0.30oo Cu (Engineering and deposits. In addition, suspected Oligo- Copper Flat; Copper Flat is a high-grade Mining Journal, 1976; G1les, 1995). cene-Miocene porphyry copper deposits hypogene deposit with low pyrite. The The Cunningham Gulch deposit in the are indicated by geologic data in the Copper Flat porphyry ts 75.1+2.5Ma Old Placers district is a gold-bearing, por- Organ Mountains (Newcomer and Gior- (NMBMMR unpublished age dates; phyry copper deposit (Maynard, 1995). dano, 7986; Mclemore et a1., 1996). Hedlund, 1974).Approximately 7 million Crackle breccia and stockwork veinlets of Williams and Forrester (1995) call the por- pounds of copper was produced in March tenorite, , fluorite, gold, and phyry at the Organ Mountains a pyrite through June 1982by Quintana Minerals occur in oxidized augite porphyry, which is uneconomic. Many Corp., prior to closure of the mine (Ohl monzonite surrounding the barren latite other areas in the state have potential for and Eveleth, 1984).Alta Gold Co. is cur- porphyry. Chalcopyrite occurs in unoxi- porphyry copper deposits, but there are rently applying for mining permits to dized deposits below the oxidized zone. no reported reserves or production. reopen the Copper Flat mine. Minable The latite has an age date of 29.9+1.2Ma Exploration and re-evaluation of por- reserveswere estimatedin 1984as 60 mil- (Kay, 1986; Maynard, 1995). No reserves phyry copper targets in New Mexico for lion tons oI 0.42%Cu (504million lbs Cu) afe Known. SX-EW processing will probably increase and 0.012% Mo (14.4 million lbs Mo; Geologic mapping, zoning, and geo- in the near future. Dunn, 1984). Current reserves of the chemical data from the base-metal skarn The largest porphyry copper deposit in deposit are estimated as 487 million lbs deposits and intrusive rocks in the New Mexico is the Chino mine at Santa Clr,243,000oz Au,3.2 million oz Ag, and Orogrande district led Beane et al. (1975) Rita where copper sulfides occur in the 15.7million lbs Mo (Dillard, 1995). to suggest an underground porphyry cop- upper, fractured granodiorite and adja- Supergene-enrichedcopper ore occurs per deposit possibly exists in the cent sedimentary rocks. Three periods of near the Continental skarn deposits, at Orogrande district. A granodiorite was supergene enrichment have further con- Hanover and HermosaMountains in the dated as 48.3t1.8 Ma and a latite as centrated the ore during the Eocene, early Fierro-Hanover district (Hillesland et al., 43.7t2.2 Ma by K-Ar (Beane et a1., 1975; Miocene (approximately 25 Ma), and late 1995). The tabular zones contain fine- Bloom, 1975). Drilling in the 1980s delin- Miocene-Pliocene (Cook, 1994). Adjacent grained chalcocite along fractures in the eated a resource of 335,000 tons of 0.05 copper skarns are becoming increasingly Colorado Formation (Cretaceous)and are oz/ton Au and 0.7% CUO (Strachen, more important economically. Reported 50-500 ft thick. Age dates of intrusive 1991). No other information on the por- age dates of the granodiorite stock range rocks in the Fierro-Hanover district range phyry deposit is available.

May 1996 New Metico Geology TABLE 10-sedimentary-copper and Precambriandeposits in New Mexico with reported copper production. Numbet refers to Fig. 1. *, districts with -t""t p..d".it." ft

District, County Year of Period of reported Estimated copper Host rock discovery production production (lbs)

7. Willow Creek, San Miguel 1883 7927-1944 18,687,426 Volcanic massive-sulfide deposits in Precambrian rocks 10. Pastura, Guadalupe 1900 7976-7969 13,578,214 Triassic Santa Rosa Formation 12. Gallinas, Lincoln 1885 1909-1954 8,000,000 Permian Yeso Formation 13. Nacimiento, Sandoval, 1880 1880-1964 7,700,000 Triassic Chinle Group, Permian Abo Formation, Rio Arriba* Pennsylvanian Madera Formation, veins in Precambrian rocks 65. Scholle, Socorro, 1900s 1,915-1961 7,122,468 Permian Bursum, Abo, and Yeso Formations Tortance, Valencia 75. Bent, Otero* 1900 1906-1957 560,000 Bliss Formation, Permian Abo Formation, near Tertiary dikes, veins in Precambrian rocks 66. Coyote, Sandoval, ? 1956-7957 462,000 Permian Cutler Formation Rio Arriba 67. Estey, Lincoln 1900 1900-1910 444,000 Permian Abo Formation 68. Sacramento, Otero* 1900 1900-1962 260,570 Permian Abo Formation, veins in Precambrian rocks 69. Glorieta, Santa Fe* 1900 prior to 1905 50,000 Pennsylvanian-Permian Sangre de Cristo Formation, veins in Precambrian rocks 70. Lone Eagle, Eddy 1905 1905-1956 35,236 Permian Yates Formation 77. Zuni Mountains, Cibola* 1800s 7905-1965 30,484 Permian Abo Formation, veins in Precambrian rocks 72. lemez Springs, Sandoval 1849 1928-1937 79,200 Permian Abo Formation 73. Tecolote, San Miguel 1879 1900-1954 19,112 Pennsylvanian-Permian Sangre de Cristo Formation 76. Santa Fe, Santa Fe 1880s 7956-1957 11.,766 Veins and replacements, volcanic massive-sulfide deposits in Precambrian rocks 74. Coyote Creek, Mora t847 1977-1956 10,100 Pennsylvanian-Permian Sangre de Cristo Formation 38. Black Mountain, ? 1883-1900s <10,000 Veins in Precambrian rocks, Rio Grande rift barite-fluorite-galena Dofla Ana* deposits 77. Romero Ranch, Valencia t929 7929-7956 9,300 Tiiassic Chinle Group 78. Hell Canyon, Valencia ? 7880-1976 7,900 Veins and replacements in Precambrian rocks 79. Picuris, Taos ? 7902-1955 3,400 Veins and replacements in Precambrian rocks 36. Caballo Mountains, 1 1937-1957 2,800 Veins in Precambrian rocks, sedimentary-copper deposits Sierra* 80. Placitas, Bernalillo, 1860s 7904-1967 ) 441 Triassic Chinle Group, veins in Precambrian rocks Sandoval* 81. Black Mesa, Union 1956 800 Triassic Sheep Pen Sandstone 82. Hopewell, Rio Arriba 1881-1940 400 Veins in Precambrian rocks 83. Tijeras Canyon, 1880-1952 Permian Abo Formatiory veins in Precambrian rocks Bernalillo* 84. Grandview Canyon, ? unknown Veins and replacements in Precambrian rocks Sierra 85. Ladron Mountains, ? unknown Veins in Precambrian rocks, supergene copper-uranium deposits Socorro 86. Lemitar Mountains, ? unknown Veins in Precambrian rocks, Rio Grande rift barite-fluorite-galena Socorro deposits 87. TWinning, Taos ? unknown Veins in Precambrian rocks

In the Organ Mountains, disseminated economic deposit is low (Luddington et deposits (North and Mclemore, 1986, copper and molybdenum minerals have aI., 1988; Mclemore et a1.,1996). 1988; Hill, 1993). This type of deposit dif- been found in drill holes northwest of fers from Rio Grande rift barite-fluorite- Organ and may represent a faulted por- Mississippi Valley-type deposits galena deposits by association with a tion of a porphyry copper-molybdenum marine basin in contrast to the association deposit (Newcomer and Giordano, 1986). Mississippi Valley-type (MVT) deposits of Rio Grande rift deposits in New Mexico The Sugarloaf Peak quafiz monzonite is are low-temperature, lead-zinc deposits with continental bisins along the Rio the host and has been dated as 34.4+0.3 generally found in carbonate rocks near Grande rift. The MVT deposits in New Ma (aoAr/3eAr, hornblende, Mclemore et the margins of marine sedimentary basins Mexico consist of open-space fillings in a1.,1995).Alteration, metal zonations, and without any associated volcanic or intru- breccia zones with little or no replace- drilling indicate that at least three por- sive activity. Small deposits occur adjacent ment. The deposits are small/ highly oxi- phyry systems probably occur in the to the marine Permian Basin in southeast dized, and contain only minor amounts of Organ Mountains, but the potential for an New Mexico and may be oxidized MVT lead, silver, copper, and zinc. Geochemical

NewMexico Geology May 1996 33 and stable-isotope data suggest these mined for copper. The deposits are low (Robertson et al., 1986). deposits were formed by basin brines, grade, low tonnage, and inaccessible to Ore deposits typically occur as several possibly related to migration of oil and existing mills. They are generally too low stratabound lensoid bodies that are con- gas deeper within the basin during the in silica to be suitable as silica flux mater- formable with layering and metamorphic Oligocene-Miocene uplift of the Delaware ial. Resources are reported for only the fabric (Robertson et aI., 1986). Pyrite and Basin (Hill, 1993). Production has been Nacimiento mine, which contains 6 mil- pyrrhotite in varying amounts occur with insignificant and economic potential is Iion tons of ore at a grade of 0.56% Cu and chalcopyrite, sphalerite, magnetite, Iow (North and Mclemore, 1986,7988). 13 million tons of ore at a grade of 0.48'/" , and galena. Chloritization, sili- Cu as of 5/2/80 (NMBMMR files). An in cification, and argillization occur adjacent Sedimentary copper deposits situ leaching project is proposed for the to most deposits. deposit, but poor recovery, low perme- Many ofthe VMS deposits and suspect- Stratabound, sedimentary copper depo- abilitv, and environmental concerns have ed deposits occur in or near wilderness sits containing coppet silver, and locally hampered the project for years. If in situ areas and cannot be developed in the fore- gold, lead, zinc, uranium, vanadium, and leaching of these deposits becomes feasi- seeable future. The Pecos mine (Willow molybdenum occur throughout New ble and economic, then copper might be Creek district) is currently being Mexico (Table 10). These deposits also recovered from some of the larger reclaimed. Exploration drilling continues have been called "red-bed" or "sand- deposits. at Jones Hill (Santa Fe district) to delineate stone" copper deposits by previous work- reserves in that area. Estimates from drill ers (Soul6, 1956; LaPoint, 1979; Cox and Vein and replacement deposits data suggest that the Jones Hill deposit Singer, 1986). They typically occur in in Precambrian rocks may contain a resource of over 5 million bleached gray, pink, green, or tan sand- tons of ore containing 0.89% Cu,1.98"h Zn, stones, siltstones, shales, and limestones Vein and replacement deposits contain- 0.27% Pb, and some gold and silver within or marginal to typical thick red- ing predominantly precious metals with (Dixon and Sealy, 1979; McLemore, 1995). bed sequences of red, brown, purple, or local base metals occur sDoradicallv Additional deposits may be discovered in yellow sedimentary rocks deposited in throughout most of the Precambrian tei- other Precambrian terranes. fluvial, deltaic, or marginal-marine envi- ranes in New Mexico (Fig. 1). Production AcrrtowlrucMENTs-This paper is a ronments of Pennsylvanian, Permian, or of copper has been insignificant from summary of the copper resources in New Triassic age. Some deposits (Table 10) are most districts unless sedimentary copper Mexico. Robert North and Ibrahim in sedimentary rocks that unconformably deposits also occur (Tables 10). Many dis- Gundiler reviewed an earlier draft of this overlie Proterozoic granitic rocks. tricts containing veins and replacements manuscript and their comments are The mineralized bodies typically occur in Precambrian rocks also contain other appreciated. Maureen Wilks assisted with as lenses or blankets of disseminated types of deposits, leading a number of the compilation of age dates. In additiory I and/ or fracture coatings of predominant- geologists to believe that Precambrian would like to acknowledge Robert North, ly chalcocite, , azurite, and chal- deposits are a significant source for Robert Eveleth, Daniel Hack, and many copyrite. The deposits in New Mexico younger deposits. Copper minerals with students over the years who assisted in range in size from 1 to 20 m thick and as gold and silver occur in quartz veins, compiling the production statistics. This much as several thousand meters long. shear zones, and as disseminations in work is part of ongoing research into min- Copper mineralization is dominant, with granitic and mafic rocks. The age of min- eral resources in New Mexico conducted some deposits containing as much as eralization is uncertain in most of these at NMBMMR, Charles Chapin, Director 40-50% copper. The sedimentary copper districts (Robertson et al., 1986; and State Geologist. deposits are typically associated with Mclemore, in press a). organic debris and other carbonaceous References material. Precambrian volcanogenic Orebodies range in size from small, con- massive-sulfide deposits Abramson, B. S., 1981,The mineralizing fluids taining less than a ton of ore (Black Mesa), resoonsiblefor skam and ore formation at the Fierro, Mexico,in light to moderate-sized deposits containing Continentalmine, New of Volcanogenic massive-sulfide deposits REE analysesand fluid inclusion studies: several hundred thousand tons of ore (VMS) contain varying amounts of cop- UnoublishedMS thesis.New MexicoInstitute of (Stauber). Most deposits were mined as per, along with lead, zinc, and silver, and Mining and Technology,Socorro, 143 pp. open pits although underground methods are associated with Precambrian green- Ahmad, S. N., and Rose,A. W., 1980,Fluid inclu- were employed locally in many districts. stone terranes. Only three districts in New sionsin porphyry and skarn ore at SantaRita, New Mexico: EconomicGeology, v. 75, pp. Copper and other metals were probably Mexico contain known VMS deposits (i.e. 229)50. transported in low-temperature solutions Willow Creek, Santa Fe, and La Virgen), Akright, R. L., 1979,Geology and mineralogyof through permeable zones during or soon and only the Willow Creek district has the Cerrillos copper district, SantaFe County, after diagenesis (LaPoint, 1,979; yielded any significant copper production New Mexico;in Ingersoll,R. V, Woodward,L. Mclemore, in press a). Oxidizing waters (Table 10). However, several additional A., and fames.H. L. (eds.),Santa Fe Country: could leach copper and other metals from districts have characteristics that suggest New Mexico GeologicalSociety, Guidebook 30, oo.257-260. (1) Proterozoic rocks enriched in these VMS deposits may (Robertson occur et al., eiten, IrA.S., and Foord, E. E., 199L,Geological, metals, (2) Proterozoic base-metal depos- 1986) and offer excellent exploration tar- geochemical,and isotopic characteristicsof the its, and (3) clay minerals and detrital gets. Many of these deposits are classified Lincoln County porphyry belt, New Mexico: grains in the red-bed sequences (LaPoint, as vein and replacement deposits in implicationsfor regionaltectonics and mineral 1979). Sources for chloride and carbonate Precambrian rocks. deposits;in Barker,J. M., Kues,B. S,Austin, G. S., Lucas, G. (eds.),Geology of the Sierra to form soluble cuprous chloride or VMS deposits are polymetallic, strata- and S. Ranges, cuprous carbonate and other metal com- Blanca,Sacramento, and Capitan New bound deposits formed contemporane- Mexico: New Mexico Geological Society, plexes occur in older Paleozoic evaporite ously with submarine volcanism by hot Guidebook42, pp. 97-113. and carbonate sequences. Precipitation saline brines. Subsequent metamorphism Allmendinger,R. J., 1975,A model for occurred at favorable oxidation-reduction or hydrothermal activity may have redis- in the Hansonburgmining district,New Mexico: interfaces in the presence of organic mate- tributed and reconcentrated new deposits. Unpubiished PhD dissertation, New Mexico Instituteof Mining and Technology,Socorro, 190 rial or HrS-rich waters. VMS deposits in New Mexico are hosted DD. Most sedimentary copper deposits in by volcanic rocks, clastic sediments, and Anderson, E.C., 1c57,The metal resourcesof New New Mexico would not be conventionally carbonate rocks, all of Precambrian age Mexico and their economic features throush

May 1996 New Mexico Geology 1954: New Mexico Bureau of Mines and Mineral New Mexico; in Titley, S. R. (ed.), Advances in Cordillera: Arizona Geological Society, Digest, v Resources,Bulletin 39, 183 pp. geology of the porphyry copper deposits: 20, pp.35-68. Armsffong, A. K., Renault, J. R., and Oscarsory R. University of Arizona Press, Tucson, pp. Lowell, J. D., 1974,Regional characteristics of por- L., 1995,Comparison of hydrotherrnal alteration 313-326. phyry copper deposits of the southwest: of Carboniferous carbonate and siliciclastic rocks Dunn, P G., 1984, Geologic studies during the , v. 69, pp. 601-617. in the Valles caldera with outcrops from the development of the Copper Flat porphyry Lowel1, J. D., and Guilbeft, J., 1970, Lateral and Socorro caldera, New Mexico: Journal of deposit: Mining Engineering, v 36, no. 2, pp. vertical alteration mineralization zoning in por- Volcanology and Geotherrnal Research,v 67, pp. 151-160. phyry ore deposits: Economic Geology, v. 65, pp. 207-220. Elston, W. E., 1,994,Siliceous volcanic centers as 373408. Aronson, J. L., and Lee, M., 1986, K/ Ar systemat- guides to mineral exploration: review and sum- Luddington, S., Hanna, W. R., Turner, R. L., and ics of bentonite and shale in a contact metamor- mary: Economic Geology, v 89, pp. 1662-1686. Jeske,R. E., 1988,Mineral resources of the Organ phic zone, Cerrillos, New Mexico: Clays and Energy, Minerals and Natural Resources Mountains Wildemess Studv Area, Dofra Ana Clay Minerals, v 34, pp. 483487. Department, 1994, Annual Resources Report: County, New Mexico: U. S. Geological Sur-vey, Atkinson, W. W., Jr., 1961, Geology of San Pedro New Mexico Energy, Minerals and Natural Bulletin 1735-D, pp. Dl-D17 . Mountains, Santa Fe County, New Mexico: New ResourcesDepartment, Santa Fe, 116 pp. Lueth, V. W, 1984, Cornparison of copper skarn Mexico Bureau of Mines and Mineral Resources, Engineering and Mining Journal staff, 1,976,In the deposits in the Silver City mining region, south- Bulletin 77, 50 pp. U.S.: Engineering and Mining JorrnaI, v. 177, no. western New Mexico: Unpublished MS thesis, Bachman, G. O., and Mehnert, H. H., 1978,New K- 9. o. 271.. University of Texas at El Paso, L79 pp. Ar dates and the late Pliocene to Holocene eeo- Gardner, J. N., Goff, F.,Garcia, S., and Hagary R. C., Marvin, R. F., and Dobson, S. W., 1979, Radio- morphic history of the central Rio Crande 1986,Stratigraphic relations and lithologic varia- metric ages: Compilation B, U.S. Geological region, New Mexico: Geological Society of tions in the Jemez volcanic fieid, New Mexico: Survey: Isochron/West, no. 26, pp. 312. America, Bulletin, v 89, pp. 283-292. Journal of Geophysical Review, v. 91., pp. Maynard, S. R., 1995,Gold mineralization associat- Beane, R. E., 1974, Barite-fluorite-galena deposits 1763-1778. ed with mid-Tertiary magmatism and tectonism, in south-central New Mexico: A oroduct of shal- Giles, D. L., 1995, Cerrillos mining district; in Ortiz Mountains, Santa Fe County, New Mexico; low intrusions,groundwater, and epicontinental Bauer, P W, Kues, B. S., Dunbar, N. W., in Bauer, P. W., Kues, B. S., Dunbar, N. W, sedlments (abs.): Geological Society of America, Karlstrom, K. E., and Harrison, B. (eds.),Geology Karlstrom, K. E., and Harrisory B. (eds.),Geology Abstracts with Programs, v. 6, no. 7, pp. 646-647. of the Santa Fe region, New Mexico: New Mexico of the Santa Fe regiory New Mexico: New Mexico Beane,R. E., Jaramillo,L., and Bloom, M.5.,1,975, Geological Society, Guidebook 46, pp. 61.-62. Geoiogical Society,Guidebook 46, pp. 161.-166. Geology and base metal mineralization of the Hanor, J. 5., 1979, The sedimentary genesis of McDowe11,F.W.,1971,, K-Ar ages of igneous rocks southern Jarilla Mountains, Otero County, New hydrothermal fluids; in Barnes, H. (ed.), {rom the western United States: Isochron/West, Mexico; in Seager, W. R., Clemons, R. E., and Geochemistry of hydrothermal ore deposits, 2nd no. 2, pp. 1.-1.6. Callender, J. F. (eds.), Guidebook of the Las ed.: John Wiley and Sons, New York, pp. Mclntosh, W. C., Kedzie, L. L., and Sutter, J. F., Cruces Country: New Mexico Geoiogical Society, 137-172. 1990, Paleomagnetic and 40Ar/3eAt dating data- Cuidebook2b, pp. 151-161. Hedlund, D. C.,L974, Age and structural setting of base for Mogollon-Datil ignimbrites, southwest- Bloom, M. 5., 1,975,Mineral paragenesis and con- base-metal mineralization in the Hillsboro-San ern New Mexico: New Mexico Bureau of Mines tact metamorphism in the Jarilla Mountains, Lorenzo area, southwestern New Mexico (abs.); and Mineral Resources,Bulletin 135,79 pp. Orogrande, New Mexico: Unpublished MS the- in Siemers, C. T., Woodward, L. A., and Mclemore, Y. T., 1994a, Volcanic-epithermal sis, New Mexico Instituie of Mining and Callender, I. F. (eds.), Ghost Ranch: New Mexico deposits in the Mogollon-Dati1 volcanic fie1d, Technology, Socorro, 107 pp. Geological Society,Guidebook 25, pp. 378-379. New Mexicoi in Chamberliry R. M., Kues, B. J., Buchanan, L. J., 1981,Precious metal deposits asso- Hill, C. A., 1993, Sulfide/baritelfluorite rnineral Cather, S. M., Barker, J. M., and Mclntosh, W C. ciated with volcanic environments in the south- deposits, Guadalupe Mountains, New Mexico (eds.), Mogollon Slope: New Mexico Geological wes! in Dickinson, W R., and Payne, W. D. and west Texas: New Mexico Geology, v. 15, no. Society,Guidebook 45, pp. 299109. (eds.),Relations of tectonics to ore deposits in ihe 3,pp. s6-65. Mclemore, V. T., 1994b, Summary of the mineral southern Cordillera: Arizona Geological Society, Hillesland, L. L., Hawkins, R.8., and Worthington, resources in the San Andres and Organ Digest, v. L4, pp. 237162. W. T., 7995, The geology and mineralization of Mountains, south-central New Mexico; in Chamberlin, R. M., Logsdon, M. J., Eveleth, R. W., the Continental mine area, Grant County, New Garber, R. A., and Keller, D. R. (eds.), Field guide Bieberman, R. A., Roybal, G. H., Osburn, J. C., Mexico; in Pierce,F. W, and Bolm, J. G. (eds.), to the Paleozoic sections of the San Andres North, R. M., Mcl-emore, V T., and Weber, R. H., Porphyry copper deposits of the Arnerican Mountains: Permian Basin Section-SEPM, 1982, Preliminarv evaluation of the nineral- Cordillera: Arizona Geological Society, Digest, v. Publication No. 9+-35, pp. 1,43-153. resource potential of the Sierra Ladrones 20,pp.473483. Mclemore, V. T., 1995, Mineral resources of the Wilderness Study Area, Socorro County, New Hollister, V. F-, L992, On a proposed plutonic por- southern Sangre de Cristo Mountains, Santa Fe Mexico: New Mexico Bureau of Mines and phyry gold deposit model: Nonrenewable and San Miguel Counties, New Mexico: in Bauer, Mineral Resources,Open-fi1e Report 179, 168 pp. Resources,v. l, pp. 103-302. P.W., Kues, B.S., Dunbar, N.W., Karlstrom, K.E., Christiansen, P. W., 1974, The story of mining in Jolly, J. L. W., and Edelstein, D. L.,1992, Copper: U . and Harrison, B. (eds.), Geology o{ the Santa Fe New Mexico: New Mexico Bureau of Mines and S. Bureau of Mines, Annual Report 1990, 110 pp. region, New Mexico: New Mexico Geological Mineral Resources,Scenic Trip 12, 112 pp. Jones, F. A., 1904, New Mexico mines and miner- Society,Guidebook 46, pp. 155-160. Cook, S. 5.,1994, The geologic history o{ super- als: New Mexican Printing Company, Santa Fe, Mcl,emore, V T., in press a, Silver and gold occur- gene enrichment in the porphyry copper 349 pp. rences in New Mexico: New Mexico Bureau deposits of southwestern North America: Kay, B. D., 1986,Vein and breccia gold mineraliza- Mines and Mineral Resources,Resource Map 21. Unpublished PhD dissertation,University of tion and associated isneous rocks at the Ortiz Mclemore, V T., in press b, Volcanic-epithermal Arizona, Tucson, 163 pp. mine, New Mexico: Unpublished MS thesis, precious-meta1 deposits in New Mexico; in Cox, D. P., and Singer, D. A., eds., 1986, Mineral Colorado School of Mines, Golden, 179 pp. Geology and ore deposits of the American deposit models: U. S. Geological Survey, Bulleiin Kolessar, 1., 1982, The Tyrone copper deposits, Cordillera: Geological Society of Nevada. 1693,379pp. Grant County, New Mexico; in Titley, S. R. (ed.), Mclemore, V T., in press c, Great Plains margin Dillard, G., 1995,Alta Gold gets funds, prepares to Advances in geology of ihe porphyry copper (alkaline-related) gold deposits in New Mexico; restart Copper Flat: Southwestern Pay Dirt, deposits: University of Arizona Press, Tucson, in Geology and ore deposits of the American February, p. 11A. pp.327133. Cordillera: Geological Society of Nevada. Dixoru R. L., and Seay,M.W.,1979, Pecosproject, Kottlowski, F. E., and Steensma,R. 5., 1979,Barite- Mcl,emore, V T., and Barker, J. M., 1985, Barite in State of New Mexico, Santa Fe and San Miguel fluorite-lead mines of Hansonburg rnining dis- north-central New Mexico: New Mexico Counties, massive sulfides, copper-lead-zinc- trict in central New Mexico: New Mexico Geology, v. 7, no. 2, pp. 21-25. gold-silver: Unpublished report, Continental Oil Geology,v. 1, no. 2, pp. 17-20,32. Mclernore, V T., and Lueth, V W., 1995, Co., in Anaconda Geoloqical Document LaPoint, D. 1., 1979, Geology, geochemistut and Carbonate-hosted lead-zinc deposits in New Coffection. University of Wyomirg, #43512.05, petrology of sandstone copper deposits in New Mexico (abs.): Society of Economic Geologists, 123 oo. Mexico: Unpublished PhD dissertation, Intemational Field Conference on Carbonate- DuHamel, J. E., Cook, S. S., and Kolessar, 1., 1995, University of Colorado, Bou1der,333 pp. hosted Lead-Zinc Deposits, Extended Abstracts, Geology of the Tyrone porphyry copper deposit, Lindgren, W, Graton, L. C., and Gordon, C. H., oo.209-21L. New Mexico; in Pierce, F. W, and Bo1m, J. G. 1910. The ore denosits of New Mexico: U. S. Milemore, V T., Mclntosh, W C., and Pease,T. C., (eds.), Porphyry copper deposits of the CeologicalSurr ey.Professional Paper 68,36 I pp. 1995,40Ar/3eAr age determinations of four plu- American Cordillera: Arizona Geological Societt Long, K. R., 1995, Production and reserves of tons associated with mineral deoosits in south- Digest, v. 20, pp. 464472. Cordilleran (Alaska to Chile) porphyry copper western New Mexico: New Melico Bureau of Dunn, P G.,1982, Geology of the Copper Flat por- deposits; in Pierce, F. W,. and Bolm, J. G. (eds.), Mines and Mineral Resource, Open-file Report phyry copper deposit, Hillsboro, Sierra County, Porphyry copper deposits of the American 41.0,36pp.

New Mexico Geology May 1.996 Mcl-emore, V. T., and North, R. M., 1984, mining the origin of ore deposits of the Sully, J. M., 1908, Report on property of Santa Rita Occurrences of precious metals and uranium in Mississippi Valley type-Part II: Economic Company situated in Grant County, New the northern Rib Grande rift, New Mexico; in Geology, v. 75, pp. 1,61-172. Mexico: Unpublished reoort on file at New Baldridge, W. S., Dickerson, P W, Riecker, R. E., Osterberg, M., and Muller, P.,1994, Geology of the Mexico Bure^auof Mines and Mineral Resources, and Zidek, l. (eds.), Rio Grande rift: northern Cyprus Pinos Aitos deposit; in Trip 10 and 13; 96oo. New Mexico: New Mexico Geological Society, Tyrone, Pinos Altos, Chino, Continental, Central Thompson, T. 8.,199Ia, The Bonito-Nogal district, Guidebook 35, pp. 205-212 district, New Mexico: Arizona Geological Lincoln County, New Mexico (abs.): Geological Mcl-emore, V T., Sutphin, D.M., Hack, D.R., and Society, Bootprints along the Cordillera, Field Society of America, Abstracts with Programs, v Pease, T. C., 1996, Mining history and mineral Guide,29pp. 23.o.99. resources of the Mimbres Resource Area, Dofla Perhac, R.M., 1970, Geology and mineral deposits Thompson, T.8., 1q91b,The Lincoln Cou:rty por- Ana, Luna, Hidalgo, and Grant Counties, New of the Gallinas Mountains, Lincoln and Torrance phyry belt, New Mexico (abs.): Geological Mexico: New Mexico Bureau of Mines and Counties, New Mexico: New Mexico Bureau of Society of America, Abstracts with Programs, v. Mineral Resources,Open-file Report 424. Mines and Mineral Resources,Bulletin 95,51 p. 23.p.99. Megaw, P K. M., Ruiz, J., and Titley, S. R., 1988, Phelps Dodge Corporation, 1995,Annual Report Titley; S. R., and Marozas, D. C., 1995, Processes High-temperature, carbonate-hosted Ag-Pb- for the year 1994: Phelps Dodge Corp., 66 pp. and products of supergene copper enrichment; Zn(Cu) deposits of northern Mexico: Economic Renault, J., Armstrong, A. K., Repetski, J. E., and in Pierce, F. W, and Bolm, J. G. (eds.), Porphyry Geology, v 83, pp. 1856-1885. Oscarson, R. L., 1995, Geology, mineralogy, geo- copper deposits of the American Cordillera: Meinert, L. D.,1987, Skam zonation and fluid evo- chemistry, and geothermometry of Ke1ly Arizona Geological Society Digest, v. 20, pp. lution in the Groundhog mine, Central mining Limestone jasperiods, Magdalena mining dis- 156-768. district, New Mexico: Economic Geology, v. 82, trict, New Mexico: New Mexico Bureau of Mines Turner, D. R., 1990, Geochemistry, stable isotopes, PP. 523-54s. and Mineral Resources,BulJetin 152,50 pp. and fluid flow of the Empire zinc skarns, Central Milbauer, J. A., 1,982,The historical geography of Robertson, J. M., Fu1p, M. S., and Daggett, M. D., mining district, Grant County, New Mexico: the Silver City mining region of New Mexico: III, 1986,Metallogenic map of volcanogenic mas- Unpublished PhD dissertation, University of Unpublished PhD dissertation, University of sive sulfide occurrences in New Mexico: U. S. utah, salt Lake City, 295 pp. California, Riverside, 413 pp. Geological Survey, Miscellaneous Field Studies Turner,D. R., and Bowman,I.R.,1993, Origin and Newcomer, R. W., Jr., and Giordano, T. H., 1986, Map MF-1853-A, scale 1:1,000,000. evolution of skarn fluids, Empire zinc skams, Porphyry-iype mineralization and alteration in Rytuba, J. J., L98L, Relation of calderas to ore Central mining district, New Mexico, U. S. 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(eds.), Santa Rosa-Tucumcari region: New of the Raton-Springer area, Colfax and Union Government Printing Office, Washington, D.C., Mexico Geological Society, Guidebook 36, pp. Counties, New Mexico: U.S. Geological Survey, variously paginated. 301-305. Professional Paper 1507,58 pp. Van Alstine, R.8., 1976, Continental rifts and 1in- North, R. M., and Mclemore, V. T., 1986,Silver and Seager,W. R., Hawley, J. W., and Clemons, R. E., eaments associated with major fluorspar dis- gold occurrences in New Mexico: New Mexico 1971,Geology of San Diego Mountain area, Dofla tricts: Economic Geology, v.71., pp- 977-987. Bureau of Mines and Mineral Resources, Ana County, New Mexico: New Mexico Bureau Wargo, J. G., 1964,Geology of a disseminated cop- Resource Map 15, 32 pp., scale 1,000,000. of Mines and Mineral Resources, Bulletin 7, 38 per deposit near Cerrillos, New Mexico: North, R. M., and Mclemore, V. T., 1988,Aclassifi- DD. 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New Mexico GeologicalSociety 1996Fall Field Conference

The 1996 NMGS Fall Field Conference will examine the geology of the Los Alamos,/Iemez Mountains and Nacimiento Mountains area on September 25-28. This scenic and geologically diverse region includes spectacular Tertiary-Quaternary volcanism, includ- ing the 14-mi-wide Valles caldera, an excellent record of Rio Grande rift faulting and sedimentation, a complex Tertiary-Quaternary record deposition and erosion by the Rio Grande, a thick and richly fossiliferous late Paleozoic section, and much more. The guidebook for the conference will be an approximately 400-page, hard-bound book containing three major road logs and 35-40 contributed papers. Cochairmen are Margaret Anne Rogers and Barry S. Kues. For more information on the field conference, refer to World Wide Web : htq :/ / XRFMAC. lanl. gov,/ nmgs1996.html New Mexico Geology,v. 18, no. 1, p.13.

May 1996 New Mexico Geology