Tujuh Bukit Deposit, Banyuwangi Province, East Java, INDONESIA

Mineralisation Styles

Julian Bartlett

PT Merdeka Copper Gold

The Pliocene Tujuh Bukit deposit is located in East Java, Indonesia. It comprises near-surface high sulfhidation Au-Ag mineralisation that is telescoped down deep-seated faults onto a large underlying porphyry Cu-Au-Mo system. The top of the system is weathered, with oxide gold mineralisation well developed in the near-surface environment. The deposit represents a unique opportunity to study a preserved hydrothermal system displaying classic characteristics of high sulfidation, intermediate sulfidation, and porphyry-style mineralisation observed over 1,000 vertical metres.

First ore was placed under irrigation on the heap leach pad in February 2017 with first gold production in March 2017. Total life of mine production of 1.2 million recoverable ounces of gold and 4.7 million recoverable ounces of silver is planned over the remaining 8 years of mine life for the oxide project.

Near surface high sulphidation mineral resources are presently 106 Mt at 0.73 g/t gold and 24 g/t silver containing 2.5 Moz of gold and 80 Moz of silver. Ore reserves of 48 Mt at 0.90 g/t gold and 26 g/t silver containing 1.4 Moz of gold and 39 Moz of silver in five open pits directly overlies the large porphyry sulphide system with resources of 1.9 Bt at 0.45% copper and 0.45 g/t gold containing 19 Blbs of copper and 28.1 Moz of gold.

After a five year hiatus, now that oxide mining is well underway, BSI is now assessing the high grade upper levels of the porphyry deposit which is dominated by high sulfidation and intermediate sulfhidation mineralisation.

Deep drilling from surface is providing valuable new insights into the deposit and in parallel an exploration decline is currently being constructed to act as a drilling platform for additional resource definition drilling to inform a feasibility study for block cave mining.

*BSI is a wholly owned subsidiary of IDX listed entity PT Merdeka Copper Gold

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