Laurentian University SEG student chapter · Laurentian University SEG student chapter ......

LU-SEG student chapter. Field trip Peru 2017

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Laurentian University SEG student chapter

February 15 – 28th

International Field Trip Report Peru 2017

Prepared for: Society of Economic Geologists SEG


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Contents

List of Participants

Sponsors

Hosting companies

Itinerary

Day 1. Arrive in Lima

Day 2. Cerro Lindo Mine

References

Acknowledgements

Day 3. Condestable Mine

References

Acknowledgements

Day 4. Driving to Tarma

Day 5. Pasco MILPO Complex

References

Acknowledgements

Day 6. Driving to Trujillo

Day 7. Driving to Cajamarca

Day 8. Cerro Corona Mine

References

Acknowledgements

Day 9. Yanacocha Mine

References

Acknowledgements

Day 10. Driving to Lima


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Participants:

NAME CITIZENSHIP Position

Elizabeth Turner Canadian LU-Faculty

Daniel Kontak Canadian LU-Faculty

Yiguan Lu Chinese PhD student

Christopher Beckett-Brown Canadian MSc student

Natascia Zuccarelli- Pegoraro Canadian MSc student

Jacqueline Huggins Canadian MSc student

Andrew Bradley Canadian BSc student

Mothepana Francisca Maepa South African MSc student

Matthew Brown United Kingdom BSc student

Charles Scott Spath United States MSc student

Philippe Gerald Eric Trudel Canadian MSc student

Sarah Clay United Kingdom PhD student

Marie Létourneau Canadian MSc student

Luis Arteaga Colombian MSc student

Thomas Ogilvie Canadian MSc student

Ian Newman Canadian MSc student

Malose Michael Langa South African MSc student


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Sponsors

The Laurentian University SEG student chapter (LU-SEG) wishes to thank the following

companies and organisations who, through their generous contributions, have helped to

make this field trip possible.


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The LU-SEG student chapter is particularly grateful for

the assistance given by:

A special thank you to the Society of Economic Geologists (SEG) which

through the Stewart R. Wallace Fund helped to make this trip possible for

the student participants of the LU-SEG student chapter. The overall funds

raised for the 12-day international field trip was used to cover

accommodation, transportation, insurances, and medical examinations. Final

cost for each student participant amounted to $825CAD which was the cost

flights (Toronto, CA to Lima, Peru).


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Hosting companies

The LU-SEG chapter would also like to acknowledge the support of the following both

Peruvian and International mining companies, who kindly accepted to host the LU-SEG

visit, to share their time and geological knowledge.


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LU-SEG Peru trip February 15-28th, 2017 Itinerary

Day Plan

1 – Feb 15th Depart from Toronto (15th evening)

2 – Feb 16th

Day in Lima, medicals, tourism

3 – Feb 17th Depart Lima early in the morning, drive to Chincha and go directly to Cerro Lindo Mine (overnight in Pisco)

4 – Feb 18th

Early morning departure, head to Raul Condestable Mine

Drive to Lima (overnight in Lima)

5 – Feb 19th Early morning departure, drive to Tarma, 3000 m.a.s.l (overnight in Tarma)

6 – Feb 20th

Early morning departure, visit Cerro de Pasco MILPO mine, 4400

m.a.s.l Finish visit between 12-1 pm (drive to Lima + overnight. ETA 8 pm)

7 – Feb 21st Driving from Lima to Trujillo (overnight Trujillo)

8 – Feb 22nd

Driving from Trujillo to Cajamarca

(overnight Cajamarca)

9 – Feb 23rd

Early morning departure visit Cerro Corona Mine

Afternoon: Visit Goldfields core shack (overnight Cajamarca)

10 – Feb 24th

Early morning departure, Yanacocha tour (full day)

(overnight Cajamarca)

11 – Feb 25th

Early morning departure from Cajamarca back to Lima

(overnight Lima)

12 – Feb 26th

Arrive in Lima (4-6 am)

Full day for tourism

13 – Feb 27th

Full day for tourism

Arrival Lima Airport at midnight

14 – Feb 28th

Arriving to Toronto 11:00 am


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Day 1. Arrive in Lima

First day participants arrived in Lima from Toronto and spent the day touring Lima

ending with a group dinner at the Miraflores beach


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Day 2. Cerro Lindo Mine

Geology

The Cerro Lindo deposit is located ~240 km south of Lima, in the district of Chavin at 1820 m.a.s.l. Cerro Lindo is a Zn/Cu/Pb/Ag VMS deposit, wholly-owned and operated by Milpo, a subsidiary of Votorantim Metais Holding. The deposit is hosted by a sequence of volcanic and sedimentary rocks belonging to the Huaranguillo Formation (Mid to Late Cretaceous), equivalent to the Casma Group and Copara Formation in other regions of Peru. These volcanic rocks form a roof pendant over the Coastal Batholith (Late Cretaceous to Early Tertiary). Portions of the batholith outcrop NE and SE of Cerro Lindo with tonalitic to dioritic composition and later intrusions of monzonites and granodiorites. These intrusions generated contact metamorphism, lifting, and faulting of the Huaranguillo volcano-sedimentary sequence. Within the project area the sequence is composed by hornfels, nodular schists, andesites, dacites, and rhyolites. All these units are intruded by discontinuous andesitic and pegmatitic dykes. Two different types of mineralization occur at Cerro Lindo: Zn-Cu-Ag massive sulfide orebodies with zones of secondary enrichment, and irregular Pb-Ag-Cu-Zn veins. Four main sulfide orebodies are recognized in Cerro Lindo. They vary from massive to semi-massive, with banded, stockworked, or disseminated distribution of sulfides. These orebodies make a resource of ~75 million tonnes at 1.41 oz Ag/ton, 0.94%Cu, 0.36%Pb, 2.84%Zn. The most abundant sulfide is pyrite, followed by sphalerite, chalcopyrite, and galena; traces of pyrrhotite, molybdenite and arsenopyrite are also present. Secondary supergene sulfides are mostly chalcocite and covellite, and the most important no-metallic mineral is barite. Some of the low-grade bodies increase their grade close to the intersection with quartz-galena-chalcopyrite-sphalerite. From footwall to hanging wall, the mineral zonation is chalcopyrite, sphalerite, galena, and barite.


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Production Cerro Lindo is the sixth largest Zn mine in the world and the largest Peruvian underground mine. Production started in 2007 with 5 ktpd, and after three subsequent expansions, the mine reached its current capacity of 18 ktpd in 2014. An ongoing expansion will raise the production to 20 ktpd in 2018. Cerro Lindo is the first mine in Peru to use desalinated seawater for its operation, piping water 60 km up from the Pacific Ocean to the mine. The Figure 2 shows Milpo´s excellent track record of increasing production capacity incrementally without impacting the existing operations.


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Students received a presentation about Cerro Lindo´s geology and descriptions of

the different lithologies and mineralization styles at the core shack by geologist Jean Paul Bueno (MILPO) as well as a short review on VMS deposits by LU

professor Dr. Dan Kontak

“Yellow Ore”, massive pyrite with minor chalcopyrite (~1% Cu)


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“Black Ore”, massive sphalerite, galena, and barite.

Underground at Cerro Lindo


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References

TripleFlag, 2016. Cerro Lindo Silver Stream, cornerstone asset.

INGEMMET, 2004. Compendio de yacimientos Minerales del Perú. Capitulo XVIII:

yacimientos volcanogénicos marinos de sulfuros masivos tipo Kuroko.

Acknowledgements

Victor Gobitz. MILPO Chief Executive Officer

Juan Carlos Ortiz. MILPO Chief Operations Officer

Enrique Garay. MILPO Geology and Exploration Manager

Zetti Gavilan. Cerro Lindo Mine Manager

Mine staff

Day 3. Condestable Mine

Geology

The iron oxide copper-gold (IOCG) Raúl-Condestable deposit is located 90 km south of Lima, Peru, and approximately 5 km from the Pacific coast. Mineralization consists mainly of replacement mantos and disseminations within permeable volcanoclastic and carbonate-rich rocks and structurally controlled veins surrounding a coeval and apparently causative intrusion of tonalitic composition emplaced in the core of a dacitic volcano. Potassic (biotite grading upward to sericite-chlorite) alteration and a poorly developed, almost sulfide-free, quartz stockwork closely border the tonalite, affecting the basaltic to dacitic Lower Cretaceous volcano-sedimentary host sequence. Ore is associated with a hydrated calc-silicate (mainly amphiboles) alteration that surrounds the biotite alteration. A hematite-chlorite (albite, epidote, calcite) alteration affects the periphery of the system. The main ore stage is characterized by two end-member mineral associations that were formed according to (1) an oxidized deposition sequence (hematite-magnetite-pyrite-chalcopyrite) occurring in and near feeder structures, and (2) a reduced deposition sequence (pyrrhotite-pyrite-chalcopyrite) found in volcanoclastic rocks and veins. Early specular hematite of the oxidized sequence is transformed to magnetite (“mushketovite”). The main ore-stage mineralization is cut by minor late-stage calcite-sulfide veins. The ore typically consists of chalcopyrite, pyrite, pyrrhotite, and magnetite, found as disseminations, mantos, and veins in amphibolitized rocks belonging to a Lower Cretaceous volcano-sedimentary sequence. Two main contrasting genetic models have been proposed for this deposit. In the first, ore was interpreted to have been deposited syngenetically through volcano-exhalative processes at or near the sea floor (Ripley and Ohmoto, 1977, 1979; Wauschkuhn, 1979; Cardozo, 1983). The second view considers that the deposit formed by a single epigenetic hydrothermal process, which overprinted the whole volcano-sedimentary sequence. Atkin et al. (1985) and Vidal et al. (1990) proposed an “amphibolitic Cu-Fe skarn type” for Raúl-Condestable and other deposits located south on the Peruvian coast (Eliana, Monterrosas, Marcona, and Acari). More recently, Barton and Johnson (1996), de Haller


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(2000, 2006), de Haller et al. (2001,2002, 2006), Injoque (2002), Sillitoe (2003), and Williams et al. (2005) classified Raúl-Condestable as iron oxide copper gold type (IOCG), based on its mineral association, related alteration, and style of mineralization (disseminations, mantos, and veins). The deposit area consists of a series of volcanic, plutonic, and sedimentary units of Upper Jurassic to Lower Cretaceous age, which are part of a large volcanic island-arc to continental-arc system that was active from Late Jurassic to Early Tertiary. This system includes both the Peruvian Coastal batholith and the western Peruvian through volcano-sedimentary sequence, cropping out for more than 1,000 km along the Peruvian coast (de Haller et al., 2006; and references therein). A geologic section through the Raúl-Condestable deposit is given in Figure 1, Most of the volcanic rocks in the volcano-sedimentary sequence consist of basalt and basalt-andesite (units I, III, and V). Intermediate magmatic activity took place between 116.7 ± 0.4 and 114.8 ±0.4 Ma (Aptian), with the emplacement of unit IV dacite and andesites, quartz-diorite porphyry and tonalites, grouped into the Raúl-Condestable super-unit of the Peruvian Coastal batholith (Fig. 1). Magmas of this super-unit were characterized by high water content, which contrasts with the comparatively dry basaltic to basaltic-andesitic activity that predominated before and after its emplacement. The IOCG mineralization, dated at 115.2 ±0.3 Ma, is emplaced at 2- to 3-km paleodepth in the core of a volcanic center belonging to the Raúl-Condestable super-unit, surrounding the coeval tonalite 1.

Schematic cross section of the Raul and Condestable deposits


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Underground at Condestable mine

General view of Condestable mine and processing plant


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Flotation process and final copper concentrate

Condestable Core shack (left) and sulfide ore hosted by volcanic breccias (right)


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Final group photo at Condestable mine

References

de Haller, A., Corfu, F., Fontboté, L., Schaltegger, U., Barra, F., Chiaradia, M., Frank, M., and Zúñiga A., J., 2006, Geology, geochronology, and Hf and Pb isotopic data of the Raúl-Condestable iron oxide copper-gold deposit, central coast of Peru: ECONOMIC GEOLOGY, v. 101, p. 281–310. De Haller, Antoine, and Lluís Fontboté. "The Raul-Condestable iron oxide copper-gold deposit, central coast of Peru: Ore and related hydrothermal alteration, sulfur isotopes, and thermodynamic constraints." Economic Geology 104.3 (2009): 365-384. Sillitoe, R.H., 2003, Iron oxide-copper-gold deposits: An Andean view: Mineralium Deposita, v. 38, p. 787–812.

Acknowledgements

Javier Caceres. Minera Condestable Operations Manager

Roberto Rodriguez. Exploration Manager

Mine staff


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Day 4. Driving to Tarma

Central Peruvian Highway, driving up to the Andes

“Ticlio”, traditional stop on the highway. Highest railway junction in the world


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“Alpahaca”

Natural scenes at the beautiful city of Tarma (3000 masl)


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Day 5. Pasco MILPO Complex

10 km NE from the city of Cerro de Pasco, MILPO operates a mining complex consisting

of two underground operations (Porvenir and Atacocha) as well as an open pit operation

(Atacocha pit). Atacocha is one of the three mining districts located in this region of Peru

associated to Miocene magmatic activity intruding Jurassic and Cretaceous calcareous

sedimentary units, and generating several skarn and cordilleran base metal deposits.

The MILPO deposit is a Cu, Zn, Pb, Ag skarn whose proximal part is mined underground,

and shows high grade of Cu, base metals and traditional skarn mineralogy. The distal part

of the deposit is mined at surface, where several dioritic dykes with dissemination and

veining of pyrite, sphalerite and galena have grades around 1 ppm Au and 3% combined

Pb-Zn. The calcareous wallrock is partially brecciated and exhibits the same mineralization

style with galena and sphalerite disseminated, in veins, and in pockets.

Cerro de Pasco city, one of the highest cities in the world (4330 masl), and one of

the oldest mining towns in Peru. Silver and base metal mining production started in

1630


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View of the high Andes from the Atacocha pit

Atacocha open pit


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Brecciated limestones and porphyritic diorites with dissemination and veins of

sphalerite and galena

Professor Dan Kontak inspecting mineralized core from one of the exploration

drills.


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Final group photo at the highest point of the Atacocha pit (~4800 masl)

References

Baumgartner, Regina, Lluís Fontboté, and Torsten Vennemann. "Mineral zoning and

geochemistry of epithermal polymetallic Zn-Pb-Ag-Cu-Bi mineralization at Cerro de Pasco,

Peru." Economic Geology 103.3 (2008): 493-537.

Baumgartner, Regina, Lluís Fontboté, and Ronner Bendezú. "Low temperature, late Zn–

Pb–(Bi–Ag–Cu) mineralization and related acid alteration replacing carbonate rocks at

Cerro de Pasco, Central Peru." Seventh Biennal SGA Meeting, Mineral Exploration and

Sustainable Development, Athens, Millipress l. 2003.

Johnson, Robert F., Richard W. Lewis, and Guillermo Abele. Geology and ore deposits of

the Atacocha District, Departamento de Pasco, Peru. US Government Printing Office,

1955.

Acknowledgements

Victor Gobitz. MILPO Chief Executive Officer

Juan Carlos Ortiz. MILPO Chief Operations Officer

Enrique Garay. MILPO Geology and Exploration Manager

Mine staff


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Day 6. Driving from Lima to Trujillo

Full day of driving along the Panamerican highway

The beautiful city of Trujillo


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Day 7. Driving to Cajamarca

Trujillo – Cajamarca Road

The colonial city of Cajamarca


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Day 8. Cerro Corona Mine

The Cerro Corona mine is located in northern Peru on the eastern slope of the western mountain range of the Andes. The copper-gold deposit is a typical porphyry style of mineralisation situated within the Hualgayoc mining district in the northern part of the Cajamarca province, a metallogenic province hosting prolific epithermal, porphyry and polymetallic style mineralisation. The mining area is characterised by moderate to moderately steep mountainous terrain with elevations ranging from approximately 3,600 to 4,000 metres above mean sea level. The Cerro Corona copper-gold porphyry is one of 14 known Tertiary aged porphyry Cu-Au-Mo deposits and 19 epithermal gold-silver deposits located in the Cajamarca metallogenic province (CMP) of northern Peru. There are two well-mineralised districts within the CMP. The Yanacocha district in the south of the province is host to the largest producing gold mine in South America, while the Hualgayoc mining district in the north is one of the oldest mining districts in Peru and is best known for its past silver production and more recent base metal production. This well-known district has been an important silver producing area since Inca times, with more than 50 Moz of silver and significant amounts of lead, zinc and copper produced from vein and manto-type deposits since the Spanish conquest in the 16th century. The Hualgayoc mining town was established in 1771. The regional structure is characterised by large open folds of Cretaceous-aged sedimentary units, predominately limestones, with axial planes striking approximately 315° and steep south-west dips. Faulting is generally restricted to normal and oblique slip faults with offsets of a few metres to a few tens of metres. The Cerro Corona copper-gold deposit is hosted by a 600 to 700 metre diameter subvertical, cylindrical-shaped diorite porphyry emplaced in mid-Cretaceous limestone, marls and siliciclastic rocks. Within the porphyry, the copper-gold mineralisation is primarily associated with zones of stockwork quartz veining conforming to classic porphyry-type vein definition. The Cerro Corona porphyry is unusual in that it carries a very high gold content compared to other copper-gold deposits. There are at least two phases of diorite placement, only one of which is mineralised. The non-mineralised diorite is generally regarded as the last event, and is referred to as “barren core”. Most recent geological modelling strongly suggests that the Cerro Corona porphyry probably comprises four or five satellite stocks, the last two of which are barren. Early mineralisation was accompanied by moderate to strong potassic alteration, which has been commonly overprinted by late, semi-pervasive argillic alteration and locally, by structurally controlled phyllic alteration assemblages (quartz-sericite-pyrite). The intrusion has been emplaced at the intersection of Andean parallel and Andean-normal (trans-andean) structures, which is a typical feature of the


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Cajamarca metallogenic province. A dominant northeast-southwest trending fault system, running through the intrusion, is referred to as the Mariela Fault trend, which has an important relationship in the distribution of the mineralisation. There are three distinct mineralised zones within the deposit. These are identified as the Annulus zone, the northern zone and the southern zone. Each of these is treated separately in geological and resource modelling. In addition to the mineralised zones, the deposit is characterised by several domains conforming to the degree of oxidation and weathering. Supergene oxidation and leaching processes at Cerro Corona have led to the development of a weak to moderate copper enrichment blanket. This allows for the subdivision of the deposit from the surface downward, into an oxide zone, a mixed oxide-sulphide zone, a secondary enriched (supergene) sulphide zone and a primary (hypogene) sulphide zone.


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Cerro Corona open pit

GoldFields´ geologist William Mass explaining the geology of the deposit


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Visiting GoldFields´ exploration office and checking typical samples from different

zones of the mine

Typical porphyry-style veining at the Goldfields´ core shack in Cajamarca


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References

Cerro Corona Mine. Technical Short Form Report. 31 December 2012 James, John. 1995. Geology, alteration and mineralization of the Cerro Corona Au-Cu porphyry deposit. UBC MSc thesis

Acknowledgements

Nate Brewer. Exploration Vice President. Americas Region. Goldfields.

Paul Gomez. Technical Services Manager. Goldfields La Cima. Peru

Mine staff

Day 9. Yanacocha Mine

The Yanacocha Mining District in northern Perú contains the largest and most productive group of high-sulfidation epithermal gold deposits in the world. The district represents a series of high-sulfidation epithermal gold deposits characterized by the presence of magmatic-hydrothermal alteration with alunite ± pyrophyllite + quartz and gold ± copper ± silver (Turner, 1997). High-sulfidation epithermal gold deposits worldwide are characterized by the presence of zones of alunite + quartz ± pyrophyllite and other minerals typical of hypogene advanced argillic alteration that result from acid-leaching by magmatic-hydrothermal fluids concentrated in H2SO4 (Rye et al., 1992; Arribas, 1995; Rye, 2005). The ore minerals have relatively high sulfur to metal contents that form under highly acidic, oxidized, and sulfidized hydrothermal conditions (Arribas, 1995; Esra et al. 2002). At Yanacocha, clusters of high-sulfidation epithermal gold deposits developed in a N50°E direction for 15 km. Intense and widespread hydrothermal alteration related to the ore deposits was developed over a zone as wide as 8 kilometers and covers an area of over 100 km2 (Harvey et al., 1999). On a local scale, the deposit clusters have trends that follow E-W, northwest and northeast directions. Deposit clusters include the Cerro Negro and Cerro Quilish complexes in the west; the centrally located Corimayo-Tapado, Cerro Yanacocha, San Jose, and Carachugo-Chaquicocha-Quecher complexes; and the Maqui Maqui and Arnacocha deposits to the northeast (Fig. 2). La Quinua is a deposit of gold ore-bearing glacial outwash gravels eroded from the Cerro Yanacocha complex that fill a graben and cover the Corimayo-Tapado deposit (Williams and Calderón, 2000; Mallette et al., 2004). The bedrock deposits range in size from 400,000 to over 4 million ounces of gold (Harvey et al., 1999; Teal et al., 2002). Six mines presently in production are Cerro Negro, La Quinua, Cerro Yanacocha, Carachugo, San Jose, and Maqui Maqui.


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Since the initial discovery of outcrop mineralization in 1984, Yanacocha has grown to become one of the largest gold mining districts in the world. Production from 1993 to 2008 has totaled 27.1 Moz gold all from oxide-classified ores. Single-year production peaked in 2005 at 3.33 Moz gold and 1.8 Moz was produced during 2008. Average annual life of mine (LOM) production grades have varied, ranging from 1.84 to 0.65 g/t Au during this period. Operating costs from initial production in 1993 through 2008 have ranged from a low of $97 (1997) to $358 per ounce (2008). Historically, low operating costs at Yanacocha have been aided by low waste to ore strip ratios, averaging less than 0.5 during much of its operating life, due primarily to many of the original quartz dominant outcrop deposits forming topographic highs. Most ore is classified as run-of-mine, indicating that no crushing circuit is needed in the recovery process. An additional recovery characteristic is the friable nature of most of the ore, with the majority of gold present as micron-size inclusions within limonitic fractures. Life-of-mine (LOM) recovery has exceeded 70 percent, whereas by-product silver recovery averages less than 10 percent. Silver to gold ratios in the oxide ores LOM have averaged approximately 20:1. The first reported oxide-classified resource at Yanacocha in 1988 consisted of 1.97 Moz gold, averaging 2.6 g/t. Discovery and growth curves during the 1990s reflected the phenomenal metal endowment and exploration success in the district, where gold reserves of oxide-classified ores within the district peaked in 2000 at 36.6 Moz. Reported remaining oxide reserves at the end of 2008 stood at 13.5 Moz.

Regional geological map of the Yanacocha district


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Panoramic view of the Maqui Maqui pit at Yanacocha

Explanation of Yanacocha geology and characteristics of HS epithermal deposits. Sean McCann – Exploration Manager Yanacocha (left), Richard Pilco – Newmont

geologist (centre), and professor Dan Kontak (right)

LU student group – Maqui Maqui pit, Yanacocha


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Yanacocha Verde open pit (right) and enargite-rich hydrothermal breccia (left)

Group photo at the Yanacocha Verde pit


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Laurentian students at Newmont´s core shack

Examples of advanced argillic alteration with high sulfidation Au-Cu mineralization


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References

Chiaradia, Massimo, Daniel Merino, and Richard Spikings. "Rapid transition to long-lived deep crustal magmatic maturation and the formation of giant porphyry-related mineralization (Yanacocha, Peru)." Earth and Planetary Science Letters 288.3 (2009): 505-515. Teal, Lewis, and Alberto Benavides. "History and geologic overview of the Yanacocha mining district, Cajamarca, Peru." Economic Geology 105.7 (2010): 1173-1190. Longo, Anthony A., et al. "Evolution of calc-alkaline volcanism and associated hydrothermal gold deposits at Yanacocha, Peru." Economic Geology 105.7 (2010): 1191-1241. Acknowledgements

Sean McCann. Exploration Manager Yanacocha. Newmont Mining.

Richard Pilco. Mine Geologist Yanacocha

Juan Jara. Medical Superintendent. Minera Yanacocha.

Mine staff

Day 9. Driving back to Lima

Once back in Lima, the students had 2 days to explore the city and enjoy the Peruvian

culture.

Lima tourism

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