SIMEXMIN 2010 – IV BRAZILIAN SYMPOSIUM OF MINERAL EXPLORATION

Geologic Overview of the

Yanacocha Mining District

Cajamarca, Northern Peru

Carlos Loayza – Jesus Reyes

Minera Yanacocha S.R.L.

•Introduction

•Regional Geology

•District Geology

•Deposit examples

Outline

Newmont

51.35%Buenaventura

43.65%

IFC

5.00%

Location and Ownership

LimaNewmont

51.35%Buenaventura

43.65%

IFC

5%

Yanacocha

0.1

0.3

0.6

0.8

1.1

1.3

1.71.8

1.9

2.3

2.93.0

3.3

2.6

1.6

1.8

2.1

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

Mil

lio

n o

z

1993 1995 1997 1999 2001 2003 2005 2007 2009

Year

Production Profile - Million oz

1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009

1.77 1.84 1.56 1.57 1.48 1.54 1.28 1.08 1.02 0.79 0.93 0.95 0.88 0.87 0.65 0.72 0.77

149 135 119 107 95 104 111 96 123 134 129 138 151 202 356 358 362

Year

Grade (g/t)

Total cash cost ($/oz)

Production Profile

4 . 04 . 9

6 . 1

13 . 9

2 0 . 6

3 2 . 9

3 6 . 6

3 4 . 23 2 . 6

3 1. 7 3 2 . 2 3 2 . 6

2 9 . 3

2 7 . 6

2 4 . 8

2 2 . 3

0.0

5.0

10.0

15.0

20.0

25.0

30.0

35.0

40.0

Mill

ion

oz

1994 1996 1998 2000 2002 2004 2006 2008

Year

Reserve Million oz

Yanacocha Conga

1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009

400 400 400 400 350 325 300 300 300 325 375 400 500 575 725 800

Year

Gold price ($)

Reserves

•Pre-Inca mining (mercury)

•1968 Nippon Mining - 13 holes (Cu)

•1969 - 1971 BGS regional stream sediment survey

•1981 Cedimin (BRGM) follow-up of BGS Pb and Ag anomalies

•1983 Newmont visited the area for first time

•1984 Joint Venture signed with Cedimin / Buenaventura

•1985 Drilling - low grade Ag resource + narrow Au

•1986 - 1995 Discovery of Yanacocha Sur + Norte, Carachugo, Maqui Maqui,

San José, Encajon, Cerro Quilish and Cerro Negro.

•1993 Carachugo production

•1996 - 1998 Discovery of La Quinua, El Tapado and Chaquicocha Sur Deposits

•1999 - 2000 Discovery of Corimayo (blind oxide) Deposit

•2000 Begin Exploration of District-Scale Au-Cu Sulfide Potential

•2001-2003 New models of Exploration, discovery of Chaquicocha Alta, and

Antonio.

•2004 Discovery of Cerro Negro Deep Oxide and Giuliana Deposits

•2005 Focus in Chaquicocha high grade sulfide

•2006 Focus in Yanacocha verde, Au-Cu sulfide mineralization.

•2008 - 2009 Discovery of Crater (Cu-Au mineralization), re-assessment gravel deposits.

History

Au-Cu Porphyry deposits

Au HS deposits

Base metal deposits

Cerro Corona

La Zanja

Conga

Michiquillay

Regional Geology

Galeno

Sipan

Tantahuatay

765000

765000

770000

770000

775000

775000

780000

780000

92

20

00

0

92

20

00

0

92

25

00

0

92

25

00

0

92

30

00

0

92

30

00

0

92

35

00

0

92

35

00

0

Cerro Quilish

La Quinua

Complex

Yanacocha

Chaquicocha

Maqui Maqui

0 500

Scale (m)

UP

PE

R A

ND

ES

ITE

SE

QU

EN

CE

PY

RO

CLA

ST

IC S

EQ

UE

NC

EY

AN

AC

OC

HA

LO

WE

R A

ND

ES

ITE

SE

QU

EN

CE

BA

SE

ME

NT

Ki

Km

BxF

BxF

Diatreme YPqQuaternary

Gravels

CR

ET

AC

EO

US

MIO

CE

NE

MIO

CE

NE

MIO

CE

NE

Diatreme

Dacite Porphyry

Quaternary Gravels

District Geology - Lithology

765000

765000

770000

770000

775000

775000

780000

780000

92

20

00

0

92

20

00

0

92

25

00

0

92

25

00

0

92

30

00

0

92

30

00

0

92

35

00

0

92

35

00

0

Cerro Quilish

La Quinua

Complex

Yanacocha

Chaquicocha

Maqui Maqui

Legend

Opaline

Granular Silica

Vuggy Silica

Massive Silica

Alunite Quartz

Silica Clay

Clay

Propylitic

Fresh Rock

Marble

Sericite/Illite-Pyrite

Skarn

District Geology - Alteration

Au Contours Surface Geochemistry - Structures

9230000 mN

78

00

00

mE

9225000 mN

78

00

00

mE

9220000 mN

77

00

00

mE

77

00

00

mE

77

50

00

mE

77

50

00

mE

76

50

00

mE

9225000 mN

9230000 mN

9220000 mN 76

50

00

mE

< 0.100

GEOCHEM Au

> 5.000

0.100 - 0.350

0.035 - 1.000

1.000 - 2.500

2.500 - 5.00

C° Quilish

C° Negro

Pabellon San Jose

Carachugo

Chaquicocha

Quecher

Arnacocha

Maqui Maqui

Antonio

C° Yanacocha

* +90,000 samples

District Geology

78

50

00

mE

9230000 mN

9235000 mN

9240000 mN

9225000 mN

78

50

00

mE

9220000 mN

77

50

00

mE

78

00

00

mE

77

50

00

mE

78

00

00

mE

76

50

00

mE

77

00

00

mE

76

50

00

mE

77

00

00

mE

76

00

00

mE

9230000 mN

9235000 mN

9240000 mN

9225000 mN

76

00

00

mE

9220000 mN

C° Quilish

C° Negro

Oeste

C° Negro

Este

Pabellon

SW

Pabellon

Deep

CorimayoEl Tapado

San Jose

Carachugo

Chaquicocha

Quecher

Main

Quecher

Norte Arnacocha

Maqui Maqui

Colorado

Norte

Antonio

C° Yanacocha

Giuliana

log Ohm-m

District Geology Newtem Airborne EM Survey – Resistivity Depth Slice 100m

•Favorable pyroclastic unit.

•Multi-events of breccia and intrusions.

•Structural Traps Beneath and Marginal to: Flow Dome Complexes;

Diatremes; Late-stage, High-level Intrusives.

•Mineralization beneath fresh Andesite Cap Unit.

•Potential Au-Cu sulfide mineralization below oxides.

•Examples:

Corimayo

Antonio

Cerro Yanacocha

Deposit ExamplesExploration Concepts

Get graphic with updated text

Maqui Maqui

Chaquicocha

Cerro Yanacocha

La Quinua

Deposit Examples

Antonio

Corimayo 1 km

La Quinua Pit

El Tapado

Corimayo

Deposit Examples Corimayo Deposit

3200V

11600E 11400E

3400V

OXIDE

SULFIDE

COR-59COR-66 COR-56

COR-69

24m 10.9 g/t

10m 9.1 g/t

42m 5.6 g/t

5m 4.5 g/t

6m 6.1 g/t

18m 4.1 g/t

42m 13.18 g/t

44m 17.7 g/t

High Grade Zone

Silica Granular

Clay

Cone

Silica Massive

Fresh Rock

Gold Zone 0.2 g/t

Deposit Examples Corimayo Deposit – Schematic Section 25250

Deposit Examples Antonio Deposit

Fresh upper andesite unit

Andesitic dome

Discovery outcrop, massive

and vuggy silica with barite

100m

16,4

00

16,6

00

16,8

00

17,0

00

3,600 V

3,700 V

3,800 V

3,900 V

4,000 V

4,100 V

ANT-009

ANT-029

ANT-033ANT-047

ANT-058ANT-069

ANT-071

ANT-073

ANT-074ANT-080

16,2

00

0 m 30 60 90 120 150

Upper Andesite

Dome

Maqui Maqui Ignimbrite

Lower Andesite

Dike

Coberture

Faults

Au (g/t)

0.20 - 2.000

>2.00

EXPLANATION

BA

RIT

INA

FA

UL

T

YA

FU

IST

E F

AU

LT

AG

UIL

A F

AU

LT

SULFIDE GOLD SHAPE >2g/t

16,4

00

16,6

00

16,8

00

17,0

00

3,600 V

3,700 V

3,800 V

3,900 V

4,000 V

4,100 V

ANT-009

ANT-029

ANT-033ANT-047

ANT-058ANT-069

ANT-071

ANT-073

ANT-074ANT-080

16,2

00

0 m 30 60 90 120 150

Upper Andesite

Dome

Maqui Maqui Ignimbrite

Lower Andesite

Dike

Coberture

Faults

Au (g/t)

0.20 - 2.000

>2.00

EXPLANATION

BA

RIT

INA

FA

UL

T

YA

FU

IST

E F

AU

LT

AG

UIL

A F

AU

LT

SULFIDE GOLD SHAPE >2g/t

ANT-07120m / 2.97 g/t Au / 94-114m Sf

20m / 12.66 g/t Au / 122-142 m SfANT-074

4m / 0.537g/t Au /242-246m Sf82m / 1.866g/t Au / 250-332m Sfc/26m /4.080g/t Au /260-286m Sf

ANT-07311.2m / 6.836g/t Au / 180.8-192 Sf

47.3m / 5.548g/t Au / 194.6-241.9m Sfc/ 19.4m /8.524g/t Au / 194.6-214m Sf

ANT-06951.3m / 7.53 g/t Au / 26m to 77.3m Sf

W E

Deposit Examples Antonio Deposit - Section 30500N

Deposit Examples Cerro Yanacocha Deposit

774000

774000

774500

774500

775000

775000

775500

775500

9

22

70

00

9

22

70

00

9

22

75

00

9

22

75

00

9

22

80

00

9

22

80

00

Geology Bench 3802

Se

cti

on

77

45

00

E

Legend

Cover

Dacite Porphyry

Dacitic Breccia

Andesite

Hydrothermal Breccia

Phreatic Breccia

Diatreme

Lithic Tuff

Crystal Tuff

Ultimate Pit

Deposit Examples Cerro Yanacocha Deposit - Lithology

9'226,500 N 9'227,000 N 9'227,500 N 9'228,000 N 9'228,500 N

3,500 V

3,750 V

4,000 V

3,500 V

3,250 V

Crystal Tuff

Lower Andesite

Lithic Tuff

FaultsDacitic Breccia

Phreatic Breccia

Hydrotermal Breccia

Diatreme

Dacite Porphyry

Andesite

Legend

Ultimate Pit

S N

9'226,500 N 9'27,000 N 9'27,500 N 9'28,000 N 9'28,500 N

3,500 V

3,750 V

4,000 V

3,500 V

3,250 V

Cu Shape >0.3%

Deposit Examples Cerro Yanacocha Deposit – Lithological Schematic Section

Fractured silicified fragment

silicified fragments

Legend

Granular Silica

Vuggy Silica

Massive Silica

Alunite Quartz

Clay

Propylitic

Fresh Rock

Ultimate Pit

774000

774000

774500

774500

775000

775000

775500

775500

9

22

70

00

9

22

70

00

9

22

75

00

9

22

75

00

9

22

80

00

9

22

80

00

Deposit Examples Cerro Yanacocha Deposit - Alteration

S N

9'226,500 N 9'27,000 N 9'27,500 N 9'28,000 N 9'28,500 N

3,500 V

3,750 V

4,000 V

3,500 V

3,250 V

Cu Shape >0.3%

Deposit Examples Cerro Yanacocha Deposit – Alteration Schematic Section

quartz

Fe-oxides

alunite

quartz

pyrophyllite

diaspore quartz

Legend

Shape Cu 0.3%

Shape Cu 0.5%

Shape Cu 1.0%

Ultimate Pit

774000

774000

774500

774500

775000

775000

775500

775500

9

22

70

00

9

22

70

00

9

22

75

00

9

22

75

00

9

22

80

00

9

22

80

00

Deposit Examples Cerro Yanacocha Deposit – Cu Mineralization

•At Regional scale, the Yanacocha District located in the intersection of

NE structural corridor and the NW Andean trend.

•At District scale: 1) the presence of favorable permeable rocks

(Yanacocha pyroclastic rocks) that favor the fluid flow and mineralization,

2) the multiple events of breccias and high level intrusions, and 3) the

structural setting, were key to the formation of multiple high sulfidation

centers with several overprinted events of mineralization.

•At deposit scale, feeders conduct the fluids along the favorable horizons

(Antonio), the border of dome and diatremes serves as traps for high

grade mineralization (Corimayo), multiple breccia events and intrusion

favor a long-lived system where cohesive Cu-Au mineralization in sulfides

occur below the oxides (Cerro Yanacocha).

Summary & Conclusions