About Us
Onto Deposit In the prospecting phase of 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, and it's surrounded by extreme heat. Thus, underground mining with sophisticated drying and cooling techniques is needed to develop a safe underground mine. STM aims to develop the Onto deposit into a safe and reliable underground mining operation.
2020
2022
Onto Deposit Resource Estimate Journey
The first public announcement of 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).
The second public announcement of Onto Deposit resource estimates. 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 
Prospecting Investigation and search activities to find deposits of valuable minerals. 
Pre-Feasibility Study
(STM is here since 2019) A pre-feasibility study that includes sufficient mineral exploration work, including drilling, to serve as the basis for a mineral resource report, potential ore body model, and scoping study. 
Feasibility Study Analytical studies that measure and evaluate project feasibility to provide a more concrete picture of the company's achievements and challenges in the future. 
Construction Construction involves building the mine site infrastructure and its supporting facilities. 
Mining Operation Underground mining with a block cave mining system 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.
Prospecting Investigation and search activities to find deposits of valuable minerals. Pre-Feasibility Study(STM is here since 2019) A pre-feasibility study that includes sufficient mineral exploration work, including drilling, to serve as the basis for a mineral resource report, potential ore body model, and scoping study.
Feasibility Study Analytical studies that measure and evaluate project feasibility to provide a more concrete picture of the company's achievements and challenges in the future. Construction Construction involves building the mine site infrastructure and its supporting facilities. Mining Operation Underground mining with a block cave mining system 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.