Geology Students Tour World's Largest Copper Mines in Chile

By Thomas Guengerich

SOCORRO, N.M., April 2, 2009 – Six New Mexico Tech geology students enjoyed all-access field trips to some of the world’s largest copper mines in Chile in early March.

Professor Dr. Bill Chávez led the students to six mines to learn firsthand about the mining methods, engineering, research, mineralogy and deposits.

“For students, it is a practical, educational experience,” Chávez said. “They get to see how things are done in other parts of the world and it really opens their eyes.”

All six students – five of them graduate students – raved about the trip. Sara Drueckhammer said the week in Chile was an amazing experience.

“We actually got to see and understand everything that we’ve been learning in class,” she said. “It was all right in front of our faces. As a geologist, it’s all so pertinent to see it in the field because that’s what we will be working with.”

Master’s student Shari Houston said the Chile trip was the most educationally meaningful experience in her five years at Tech.

“This trip was the most phenomenal thing a Tech student could do,” Houston said. “It was extremely impressive. Words can’t describe it. It was just a very valuable learning tool.”

The group spent a day traveling to the capital city, Santiago, then took a 20-hour, 700-mile bus ride north to the regional capital of Antofagasta. Chávez led the group on tours of five mines, two of which were near Antofagasta, with the other three tours near the inland city of Calama, which is three hours by bus northeast of Antofagasta, and is nestled in the Andean foothills.

“The biggest benefit is that the students see the stuff they are supposed to see – rocks,” Chávez said. “Importantly, they also get to see and understand new cultures. I’ve had some students go on trips to Chile and Perú, thinking that everyone south of the border eats enchiladas and that the miners use shovels, picks and burros.”

That isn’t the case in Chile, where the mining industry is mature and established.

“They have enormous trucks, huge mines and really smart geologists,” Chávez said. “It’s a cultural eye-opener for a lot of our students - they’re seeing some of the largest, most important mines in the world.”

All the students emphasized the experiential aspect – the hands-on activities and personalized tours.

“Most of the time, students only have the opportunity to learn about these things by looking at pictures or reading it in textbooks or scientific journals,” doctoral student Jesús Velador said. “Actually going into a pit and seeing the occurrence of minerals is something really great. It’s something we will always remember.”

Houston said Chávez’ experiences in geology, in mining, and in Chile were extremely helpful.

“Bill Chávez was phenomenal,” Houston said. “He took the time to explain things and he made sure we understood what we were looking at and what was going on. He translated for those of us who didn’t speak Spanish. He pushed us and questioned us and made us think for answers.”

Copper mining is a mature industry in Chile; it was among Chile’s largest industries as early as 1809, when the country gained independence. Chile became the world’s largest producer of copper in the 1860s. The country slowly began nationalizing the copper mines in the 1950s. In 1971, the Chilean government took over the entire copper industry. Many private companies are now active in Chile’s copper mining industry, but they pay heavy taxes. Today, Chile’s mines produce more than 40 percent of the world’s copper, with much of the mining activity centered in the extremely arid Atacama Desert in the northern part of that country.

In preparation for the field course, Chávez organizes and implements the itinerary for the weeklong stay, with the New México Tech Student Chapter of the Society of Economic Geologists sponsoring much of the students’ travel expenses. The Graduate Student Association and the Student Association also provided significant funding.

Each day’s excursion began with a classroom exercise. Drueckhammer said a company geologist would explain the mineralogy, operations and geologic setting of the mine. All but one company lead the group on an afternoon tour of the mine.

“We got to go to the bottom of the pits and we could see all the different alteration zones,” Drueckhammer said. “We got to collect samples, which I love, and we got to see it all – all the geology. It was pretty cool.”

The one company that didn’t offer a tour had the students examine a 100-foot core sample taken from one of their exploration projects.

“We spent a couple hours logging [geologically mapping] a core, which was really good,” Drueckhammer said. “That’s a realistic thing we would do if we were hired as a geologist at a mine.”

Houston also said the core logging experience was among her highlights because the exercise is something that a working economic geologist will be expected to master.

“The opportunity to go through an entire system and log the core from start to finish was astounding,” she said. “We got to describe what we saw – the minerals, the texture. We learned how to recognize minerals by eye and from handling it. That’s the experience I appreciate the most.”

Jesús Velador, a doctoral student, had quite a bit of experience with core logging. Before enrolling in the geology program, he had worked for more than two years at a mine in his native México. Even with his work experience, he gushed about the importance of the Chilean experience.

“I will never forget the type of minerals and the occurrence of rocks in the deposits,” he said. “The best part of the visit was seeing how they mine the minerals and how they extract the ore from the pit.”

Matt Earthman said the field trip helped with perspective. Many mineral deposits are hosted by igneous rocks formed from volcanic eruptions. Over time, natural forces alter the mineral composition of those deposits and geologists must be able to recognize these changes.

“One of the biggest things, as an economic geologist, is seeing alteration minerals,” Earthman said. “These are the things we need to be able to see to know there’s a deposit and how can we track down the big deposits. This experience put exploration into perspective. The things we saw in Chile can be applied here [in the American Southwest] too.”

Carlos Vargas, a native of Costa Rica, said the variety of mining operations was especially illuminating.

“We saw three different kinds of copper deposits,” he said. “We also learned about the paragenesis of copper and the structural geology controls. We also learned about mining methods and different mining techniques.”

Several of the mines visited are among the biggest copper mines in the world, including some deposits that comprise more than a billion tons of mineralized rock, called porphyry copper deposits, and smaller deposits that are hosted by volcanic flows [like those found in The Valley of Fire State Park]. All the students mentioned the importance of being able to see and identify large-scale deposits of various styles and types.

“We saw some text-book deposits,” Vargas said. “It’s important to read about it, but it’s more important to see it. They gave us really good talks about the deposits, then we learned about how they do it by going into the mine. That’s important because our jobs will be like that.”

“The best part of the trip for me was the visit to El Tesoro mine,” Velador said. “It wasn’t the biggest mine we visited, but the origin of the copper was very interesting – very exotic.”

Much of northern Chile is dissected by very long and active tectonic features – two of which are the West Fissure and the Atacama Fault – which bring copper from deep within the Earth’s crust to shallow levels, where it can be discovered and eventually mined. Notably, in the Atacama Desert just outside of Antofagasta, the students could see huge outcroppings of copper deposits.

“That’s not unheard of,” Drueckhammer said. “But given my experience, that’s crazy to see. At some places, we could see people prospecting for copper.”
Chávez leads at least one field trip to Chile each year. In 2008, he took two groups of students to that country, visiting different ore deposits. He’s been visiting and working in Chile every year since 1980, when he completed his doctoral dissertation on the ore deposits at Mantos Blancos, Chile.

“The company that sponsored my Ph.D. field work was very kind to me,” Chávez said. “They said, ‘Hey, kid, we have exploration programs. Tag along while you work on your thesis.’ I was introduced to many important people and many ore deposits in Chile and I’ve been going to that part of the world ever since to lead field courses and to perform consulting. The mines receive our student groups very well – always. On this last visit, two Chilean geologists came up to me and told me they missed our perennial visits … and, after almost 30 years of working in Chile, people in the mines still call me ‘Billy’.”

– NMT –