What happened

Shares of Sibanye-Stillwater (NYSE:SBGL), formerly Sibanye Gold Limited, fell over 11% today after news that a worker died at its Driefontein mining operation in South Africa. As reported by News24, over 20 workers have died at mines owned by the company this year, which is nearly half of all mining industry deaths in the country.

That was enough for mining rights groups to call for mine bosses to be held legally responsible for the deaths of workers. Whether or not laws are changed in mining-friendly South Africa remains to be seen, but it was enough to send Sibanye-Stillwater shares down 10.6% as of 3:16 p.m. EDT. It turns out there's a simple reason for the move.

A businessman holding his hand out flat with a bar chart showing losses hovering over it

Image source: Getty Images.

So what

All the negative attention could have bigger consequences for the business. That's because Sibanye-Stillwater is one of the largest platinum producers on the planet. If the company earns a reputation for not caring about the health and safety of workers (it's well on the way), then major customers could eject from their supply chains all precious metals produced by the company.

It's a major concern, especially with large materials purchasers starting to throw their weight behind worker-safety initiatives. For instance, Apple requires that all suppliers of tin, tantalum, tungsten, and gold meet certain health, safety, and income standards for laborers. It's working on similar standards for cobalt. Whether or not Sibanye-Stillwater is a supplier of any materials for Apple, it's likely to be a platinum supplier for at least a few household names -- some of which might rather avoid association with the company's safety record.

Now what

Sibanye-Stillwater stock is down 59% in the last three years and has been on a near-continuous slide since mid-2016. Considering that the company's balance sheet is relatively toxic and that the business hasn't been generating cash quickly enough to appease investors, there isn't much room for error. News of more deaths at company-owned mines is only injecting more uncertainty, causing some investors to head for the exits. Given the current situation, investors are better off avoiding the stock.