Mountain quest reveals hidden riches

A convoy of off-road vehicles was winding its way up the mountain road, kicking up clouds of dust that obscured the view. Suddenly, it came to a halt. Wang Tianyi, clad in a blue uniform, camouflage pants, and work shoes, stepped out of the first vehicle and gently carried away the calf that was blocking the way ahead.

This unexpected encounter on Jan 28, unlike past encounters with bears and wild boars, marked the start of yet another challenging day for Wang and his colleagues as they embarked on a crucial mineral exploration mission around the Lanping lead-zinc mine in the Nujiang Lisu autonomous prefecture, Yunnan province.

As the first stage of mineral exploration, the work of Wang's group involves collecting soil samples at the vertices of each 40-meter-by-100-meter rectangle, drying them in the sun, grinding them into powder, and testing their geochemical composition. With 90 percent of the work already completed, their task for that day was to sample the last and most rugged central area in the north.

"This is tough work, but every sample we collect brings us one step closer to finding new mineral deposits. And it's all worth it," the 35-year-old said.

Having commenced the project in early January, Wang is among the 33 geological workers from the Kunming General Survey of Natural Resources Center of the China Geological Survey, tasked with mapping a 44-square-kilometer surrounding area of China's largest open-pit lead-zinc mine. Braving freezing temperatures, steep slopes, and mysterious unknowns, they provide valuable insights into the region's mineral potential, facilitating the planning of future exploration and mining efforts.

Lead and zinc, often found together as co-minerals, are silvery-white metals characterized by their suitable ductility and relatively low electrical conductivity among metals. With extensive use in industrial alloys, anticorrosion coatings, and radiation shielding applications, they experience huge global demand.

In 1965, the local geological survey bureau discovered the Lanping mine, which boasts reserves of lead and zinc exceeding 15 million metric tons. It remained the largest of its kind in China until 2016, when a mine in the Xinjiang Uygur autonomous region surpassed its record.

While China ranks among the top globally in reserves for lead and zinc, the per capita availability of these metals remains limited. Moreover, the rise of new energy vehicles has further intensified demand, particularly given their critical roles in battery technologies.

Pan Jiarong, a senior engineer at the Kunming General Survey of Natural Resources Center who leads the exploration project, emphasized that prospecting near existing mines is a "low-cost, high-return" strategy, providing benefits such as economic value, resource security, and ecological protection.

He pointed to the Olympic Dam deposit in Australia as an example, illustrating how it evolved from a copper mine into one of the world's largest deposits of copper, gold, uranium, and nickel through a series of discoveries.

"Preliminary literature indicates a high likelihood of mineralization in this region. In addition, the geological structures and metallogenic conditions of known deposits often mirror their surrounding areas. This offers the potential to streamline work by utilizing existing exploration data, such as geological maps, geochemical anomalies, and drilling records, thereby reducing exploration risks and costs," Pan said.

"If new ore bodies are discovered, development can quickly proceed by leveraging existing mining infrastructure, which minimizes environmental impact from additional construction, and generates economic returns," he said, adding that this approach can also enhance regional mineralization theory.

Given Yunnan's exceptional importance as a biodiversity hot spot for flora and fauna, Pan underscored that their exploration plan was designed with a strong commitment to green exploration principles. This involves strictly adhering to the red lines that protect permanent basic farmland, conserve ecological areas, and respect urban expansion boundaries. To further minimize environmental impact, shallow drilling is chosen over the more disruptive trenching method, with careful attention paid to the disposal of waste oil and rock reagents.

"The altitude here is relatively high, which means that natural restoration of vegetation faces significant challenges. Therefore, we hope to minimize the extent of environmental disturbance as much as possible," Pan said.

The sun hung high in the sky at noon when geologist Zeng Liang and his local partner tightened the lids of their thermoses, put the empty compressed biscuit wrappers into their backpacks, and prepared to start the remaining half of their work — they were required to return to the base before 6 pm, when it got dark.

"For each geological exploration project, we generally team up a local villager with a geologist, as locals are more familiar with the mountain conditions and can look out for each other to ensure safety,"Zeng said.

He added that his local partner had worked with him for several days. Previously, the local would bring a home-cooked boxed meal, but due to the cold weather, he has taken Zeng's advice to bring biscuits and steamed buns instead.

Deep in the mountains, where telephone signals are generally weak, their emergency communication relies on the satellite phones carried in everyone's bags — both geologists and their local partners. For them, mobile phones are primarily used for recording purposes.

"We have a WeChat group where we post dozens of videos every day — surprising, thrilling, and strange ones. While our daily work can be tedious, seeing what others post not only reminds us that we're not alone but also highlights potential dangers," he said.

Zeng, like Wang, is responsible for geochemical prospecting. He pointed to a video of a colleague using a pickax to break through a 2-centimeter-thick layer of ice to collect soil samples underneath, which could reveal the region's properties.

"It's quite a unique experience, as few projects are conducted in winter," Zeng said, highlighting the daily temperature fluctuations. In the morning, they have to leave extra space in their bags for down jackets, which they take off at noon when it gets warmer.

He also emphasized the challenges posed by the local coniferous forest vegetation. Thick layers of pine needles on the ground make it extremely slippery, and many team members have slipped off slopes and grabbed onto trees to stop their fall. The rugged terrain, with slopes reaching a 40-degree incline, makes the path difficult to climb, allowing them to cover only about 1,000 meters of straight-line distance each day, with their step count exceeding 10,000.

Unlike Wang and Zeng's group, whose work is almost done, Li Jinwang's group will be engaged throughout the entire exploration project. Their responsibility is to conduct geological mapping, a crucial phase where rock characteristics — such as types, colors, textures, and structures — are accurately plotted on a topographic map at a specific scale to uncover regional geological patterns.

"To ensure uniform recording practices, my group spent the first week at the known lead-zinc mine for field training and calibrating measurement protocols," Li said, adding that for abnormal rocks that are difficult to judge, they will carefully mark the location, take clear photos, and collect a sample to bring back.

The dense vegetation in Yunnan results in a relatively thick humus layer, which presents certain challenges for their work. As Li moves from place to place, he swings a geological hammer with his right hand to strike the rocks, revealing their internal structures. With a small instrument in his other hand, he conducts preliminary tests on the rocks' elemental content and physical properties.

"It can be very frustrating if no abnormalities are found throughout the day. However, no result is also a result and needs to be dealt with seriously," he said.

Surprisingly, they have made some discoveries. For example, they have found hard gray-green rocks that exhibit a metallic luster under a magnifying glass — which is highly consistent with the characteristics of lead-zinc ores in the known Lanping deposit — suggesting a likelihood of mineral resources in the region.

Additionally, there are some findings for which they haven't yet found a definite explanation, such as rocks that emit an odor similar to asphalt when chipped and rocks with sapphire-like speckles.

"Our work in mineral exploration is like opening a blind box: we never know what we will find next, but every discovery brings us closer to unlocking the secrets of the Earth's mineral wealth. This is both the responsibility and the charm of the job I undertake," Li said.