Exploration is one of Newmont’s core competencies, and the most cost-effective way to add high-quality ounces to our reserve base. Finding and developing new ore bodies in an economically viable, environmentally responsible and socially sustainable manner is critical to Newmont’s ongoing success. Approximately 60 percent of the gold the Company will mine this year was discovered by Newmont geologists.
While gold exists across the globe at background concentrations of between two and four parts per billion, developing an economically viable mine requires ore bodies with gold concentrations of at least 2,000 to 3,000 parts per billion or higher. That is where the science of geology comes in to help us locate those rare deposits. Over the last 15 years, the exploration team has used experience, insight and the drill bit to add 123 million ounces to our gold reserves.
Geologists are not only vital to the exploration stage, but also play an important role in the ongoing discovery and recovery of gold at existing Newmont operations. Much like detectives, geologists look for clues on the earth’s surface and, using scientific deduction, work to pinpoint economically viable and recoverable concentrations of minerals and metals hidden well beneath the surface.
Our staff geologists are responsible for locating ore (rock that contains a quantity of gold that is economical to mine) and for communicating the coordinates of that ore to our engineering and operations crews. To fulfill this responsibility, our team of geologists makes its daily rounds at the mine and searches for gold in three ways: ore body analysis, ore modeling, and daily ore control.
Ore body analysis
To ensure that Newmont’s mining crews are pursuing the right ore bodies, our geologists must effectively predict and determine the location of ore underground. To design the most cost-effective and efficient drill program, geologists develop a hypothesis based on observations of the exposed rock type, structure and nearby drill holes. Core rigs (a drill specifically designed to remove a cylinder of material) are then used to remove samples of rock from the targeted area.
Geologists conduct preliminary assessments on those core samples, recording (or logging, as it’s known in the industry) the geotechnical features, lithologies (visual qualities of a rock formation), alterations, and structures of each sample. After logging is complete, the geologist will send the core samples to a lab where they will be further analyzed for quality of content – a process known as assaying.
With information gathered from the logging and assaying, geologists will then use computer software to create a 3D geologic and block model of what the ore body looks like. The information collected from core samples helps them update existing block models to accurately estimate gold resources in the ore body. In addition to using core sample data, geologists also conduct daily geologic mapping to help keep the block model for the mine up to date.
Daily ore control
As part of their rounds, geologists visit each active heading at the mine – the area that is being advanced by the mining operation. At the heading, they will draw a map of the exposed rock. This map often includes things like rock type (certain lithologies are more likely to host gold than others), structures (possible source, trap or boundary for gold bearing fluids) and alteration (does the rock look like it might have been changed from its original appearance by gold bearing fluids?).
After visiting and mapping each heading, the geologist will use the block model, geologic mapping and assay results from previous rounds, along with their understanding of the geologic controls of the deposit, to make the correct routing decision or “ore call” for the rock being mined. Finally, the geologist will update and send out a report to the operations and engineering groups with the ore call for the next day.
From start to finish
A mining geologist’s job does not end when the ore is mined and processed. Geologists must work closely with the engineers and operations crew on a daily basis to ensure that our miners continue to dig in the right direction. They are also vital to the planning and execution of concurrent reclamation and land rehabilitation efforts at Newmont, providing expert understanding of the composition, structure and needs of the land to ensure successful reclamation.
Stay tuned for our next blog in our STEM in Mining series, where we will be looking into the technologies needed to operate a safe, efficient and responsible modern gold mine.