INDONESIA GOLD RESOURCES AND EXPLORATION CHALLENGES (Source: Prihananto, 2011) Dr. Arifudin Idrus Department of Geological Engineering Gadjah Mada University E-mail address: arifidrus@gmail.com Disampaikan pada ‘One-day Course: “Pemanfaatan dan Prospek Sumberdaya Emas di Indonesia”; HMTG-UGM, 1 Oktober 2011

WHY GOLD? Part of human life since ~6,000 years ago Relatively minor occurrences, but widespread in geographic distribution Physical properties and valuable deposit Unique economic behavior (in both small and large scale)

GOLD PRODUCTION 1900-1989 (from various sources) Dutch Colonial Era Independence Sukarno | Soeharto Sumatra CoW Pacific War Ertsberg

GOLD DISTRICTS 1900-1989 Kalimantan North Sulawesi Alluvials Mangani Lebong Ertsberg Cikotok

Total: 1,768 tonnes

GOLD PRODUCTION DECREASING ??? Gold deposit potential depleted  No Decreasing of exploration activities and lack of new discoveries  ??? Technical aspects Non technical aspects

GOLD DEPOSIT TYPES Witwatersrand Greenstone Belt Epithermal including Carlin (sediment hosted) Porphyry/ skarn Orogenic Gold Volcanogenic Massive Sulfide (VMS) Others

DEPOSIT MODEL (Corbett, 2005)

REGIONAL GEOLOGY OF INDONESIA

MAGMATIC ARCS OF INDONESIA (Carlile ane Mitchel, 1994)

GOLD RESOURCES + RESERVES 1969 – 2010 (desk study) 167.66 Moz (5,214.38 tonnes) gold N: 94

GOLD – BY MAGMATIC ARC 167.66 Moz (5,214.38 tonnes) gold

GOLD – BY DEPOSIT TYPE 167.66 Moz (5,214.38 tonnes) gold

GOLD – BY PROJECT STATUS 167.66 Moz (5,214.38 tonnes) gold

GOLD MINES 1990-2010 Gosowong Mesel Buduk Mt. Muro Kencana Kelian Active Closed Sediment Hosted LS Epithermal Porphyry/ Skarn VMS ……. ……. ……. ……. Gosowong Mesel Buduk Mt. Muro Kencana Kelian Rawas Lb Tandai Mt. Muro West Pongkor Grasberg Cibaliung Cikidang Wetar Batu Hijau

PRIMARY GOLD DEPOSITS/ OCCURENCES Active Closed Sediment Hosted LS Epithermal HS Epithermal Porphyry/ Skarn Mesothermal Vein ……. ……. ……. ……. ……. Martabe Seruyung Toka Tindung Pungkut Tombulilato Jelai-Mewet Motomboto Mirah Palu Ojolali Way Linggo Wabu Awak Mas Elang Bukit Tujuh Pangulir

GEOLOGICAL TARGET TYPES HS EPITHERMAL Field SKARN Field LS EPITHERMAL Field PORPHYRY Field

GOLD MINE – LAPSE TIMES Mine Owner Status Contract Signed Production   Lebong Tandai Billiton (CSR) Closed 1985 1986 1 Gosowong Newcrest 1997 1999 2 Wetar Billiton 1991 5 Ertsberg Freeport 1967 1973 6 Pongkor Antam 1988 1994 Kelian Riotinto 1992 7 Mt. Muro Aurora 9 Kencana 2006 Mesel Newmont 1996 10 Rawas Laverton 11 Cibaliung Austindo/ Antam 1998 2010 12 Batu Hijau 13 Mt. Muro West Straits 2004 19 Grasberg 1989 22 Average Lapse Time (Years) 9.5

GOLD MINE – LIFE SPANS Porphyry VMS LS Epithermal Sediment hosted 90 91 92 93 94 95 96 97 98 99 00 01 02 03 04 05 06 07 08 09 10   Grasberg Lebong Tandai Alluvials Wetar Kelian Pongkor Mt. Muro Mesel Rawas Gosowong Cikidang Batu Hijau Mt. Muro West Kencana Cibaliung Porphyry VMS LS Epithermal Sediment hosted Alluvial

FACTORS AFFECTING INDUSTRY’S FUTURE Geological Prospectiveness (++) Country Stability (+) Gold Price (++) Legal/Commercial Basis ( - ) New Mining Law, lack of implementing regulations Intensity of Exploration Efforts (– to +)

CONCERNS IN INDONESIA (non technical aspects) Uncertainty in mineral tenement system (Mining Law No.4/ 2009 with lack of implementing regulations) Forestry overlapping issues Pains of regional autonomy Illegal mining Local community / NGOs

EXPLORATION CHALLENGES  technical aspects 1. Opportunity to generate/ develop new projects is sliming  Matured Exploration Areas 2. Exploration “going deeper” Development of new geological/ exploration model Application of new technology Advanced exploration techniques and approaches Higher exploration costs 3. Professional ability and skill of “explorationists”

MAJOR GOLD DEPOSIT TYPES IN INDONESIA Epithermal Porphyry/ skarn

Porphyry vs Epithermal