Wetar Geological Setting
The geology of Wetar Island is composed entirely of Neogene volcanic rocks and minor oceanic sediments. Submarine basaltic-andesites with local pillows form the volcanic basement to the island. The basaltic-andesites are intruded by rhyo-dacite domes and overlain by dacitic lavas, tuffs and breccias, debris flows, globerigina limestones and lahar deposits.
The age of the mineralisation has been estimated at around 4.7 million years.
Copper Mineralisation
Copper mineralisation at both Kali Kuning and Lerokis occurs predominantly within coherent massive sulphide units with a lesser amount of generally lower grade material occurring within intensely clay-sericite pyrite altered andesitic tuffs in the footwall and lateral extent of the massive sulphide units.
Based on Finders drilling, the Kali Kuning massive sulphide resource has been re-classified into three metallurgical sub-types - Leached, Transition zone and Primary massive sulphide. The Leached and Transition types reflect incipient in-situ leaching of the massive sulphide unit by natural groundwater. The Transition zone material although of lower copper grade than the main Primary massive sulphide (1 5% vs 2 9%) contains a higher proportion of readily leachable copper minerals.