About Us
Onto Deposit In 2013, Sumbawa Timur Mining (STM) discovered one of the most exciting copper-gold discoveries in the last 20 years, which we call the Onto Deposit. The Onto Deposit has its own challenges, as it is located hundreds of meters below the earth's surface, STM aims to develop the Onto deposit into a safe and reliable underground mining operation.
2020
2022
Onto Deposit Resource Estimate Journey
First public release of the Onto Deposit resource estimate. The total resource estimate is 1.7 billion tonnes, with each ton containing 0.89% copper (Cu) and 0.49 grams of gold (Au). In detail, it consists of: 
Indicated mineral resource of 0.76 billion tonnes with each ton contain of 0.93% copper (Cu) and 0.56 grams of gold (Au).
Inferred mineral resource of 0.96 billion tonnes with each ton contain of 0.87% copper (Cu) and 0.44 grams of gold (Au).
Second public release of the Onto Deposit resource estimate. The total resource estimate is 2.1 billion tonnes, with each ton containing 0.86% copper (Cu) and 0.48 grams of gold (Au). In detail, it consists of: 
Indicated mineral resource of 1.1 billion tonnes with each ton contain of 0.96% copper (Cu) and 0.58 grams of gold (Au).
Inferred mineral resource of 1 billion tonnes, with each ton contain of 0.7% copper (Cu) and 0.4 grams of gold (Au).
Mining Phase 
Exploration Exploration and drilling activities to locate mineral deposits. 
Pre-Feasibility Study
(STM’s current stage) Continued mineral exploration and drilling activities which support engineering, environmental and social studies to assess the technical and economic viability of a mining operation. 
Feasibility Study More detailed engineering, project design, environmental and social studies that determine whether construction of a mining operation is technically and economically viable. 
Construction Construction involves building the mine site infrastructure and its supporting facilities. 
Mining Operation Underground mining with a block cave mining method for mineral ore extraction. 
Mine Closure Mine closure is the period when the ore-extracting activities of a mine have ceased, and final decommissioning and mine reclamation are being completed.
Exploration Exploration and drilling activities to locate mineral deposits. Pre-Feasibility Study (STM’s current stage) Continued mineral exploration and drilling activities which support engineering, environmental and social studies to assess the technical and economic viability of a mining operation.
Feasibility Study More detailed engineering, project design, environmental and social studies that determine whether construction of a mining operation is technically and economically viable. Construction Construction involves building the mine site infrastructure and its supporting facilities. Mining Operation Underground mining with a block cave mining method for mineral ore extraction. Mine Closure Mine closure is the period when the ore-extracting activities of a mine have ceased, and final decommissioning and mine reclamation are being completed.