The news is just out that that McEwen Mining, a Canadian junior operating the El Gallo gold mine in Mexico, was robbed of 7,000 ounces of gold at gunpoint. The company is insured against robbery, as is standard in the industry, but its coverage is not enough to cover the loss of $8.4 million worth of gold.

The good news is that no one was seriously hurt, which the industry strives for and is why miners usually rely more on insurance than guns. The bad news is that what the thieves stole was not gold bars but gold in 900 kilograms of concentrate.

Here’s why this matters: Gold bars are much more compact, easy to make off with, and easy to sell, while gold in concentrate is a much bulkier commodity, needs trucks to haul, and a chemical plant to process before the crooks can see any money. This is why companies that produce gold and silver doré bars tend to have much tighter security, including armed guards. Companies that produce concentrate tend to have much lower levels of security, being primarily concerned with the safety of their trucks laden with concentrate. Until now.

We do not see this as a major game-changer, but rather as an added cost that companies that produce gold in concentrates (or that plan to do so) will have to factor in—and not just in Mexico, as word travels the world at the speed of light these days. Still, it is a significant shift in the security landscape for miners, and one investors should be aware of.