From the edge of the Kamoto Copper Company's pit, it is hard even to see the mechanical diggers toiling dozens of tiers below.
The 650-foot hole on the southern edge of the Democratic Republic of Congo is deeper than Africa's tallest building is tall. Trucks take the best part of an hour to crawl out from its heart.
The greenish ore they lug is given its hue by copper but much of its value by cobalt nestled within. Usually driven to South Africa, then often shipped to China, the cobalt will emerge from a series of factories as the priciest component of a battery powering a smartphone or, increasingly, an electric car.
A sign at the mine indicates it is 820 miles to Kinshasa, the capital, half a week's drive away. Another arrow points to a less likely destination: Baar, a sleepy suburb of Zurich, 4,000 miles away at the foot of the Swiss Alps. Located in a business park there are the headquarters of Glencore, the company that ultimately controls the Congolese mine.
Once a commodities trader that merely bought and shipped stuff others dug out of the ground, in recent years Glencore has gate-crashed an august club of global mining companies, such as Rio Tinto and Anglo American, whose histories stretch back to colonial times. Within its sprawling portfolio, Glencore is the main backer of PolyMet Mining Co., the St. Paul firm that aims to finish Minnesota's first copper-nickel mine.
Its transformation has not been problem-free, however. Glencore's dealings in Congo have landed it in a hole as deep as Kamoto. Authorities in the U.S., Canada and Britain are probing whether its executives, known in the industry for their sharp suits and elbows, deployed even sharper business practices to get ahead.
Investors have started to question the firm's prospects; its share price has slumped. Mining firms once encouraged to emulate Glencore's aggressive culture now wonder whether their old-fashioned approach might not have more merit after all.
Glencore is to mining what Goldman Sachs is to Main Street banking: nominally in the same trade but in a turbocharged way. Like the Wall Street stalwart, Glencore thrived first as a private partnership, set up in 1974 as Marc Rich + Co. Its eponymous founder gained fame as a consummate trader, and infamy for evading U.S. authorities irked by his busting of sanctions and dodging of taxes. (He was ousted from the firm in 1993, after which the company was re-christened Glencore.)