JOHANNESBURG (Reuters) - South Africa’s National Union of Mineworkers said on Friday a miner was killed by falling rocks at Sibanye-Stillwater’s Driefontein gold mine, where seven workers died four weeks ago in a cave-in following a seismic event.

Sibanye, which saw its share price sink about 28 percent in May, noted on Thursday that “recent safety incidents” were among investor concerns.

A spokesman for Sibanye confirmed the latest incident.

Safety concerns are high on the investor radar screen in South Africa’s mining industry, which extracts metals from the world’s deepest mines.

The 2017 death toll in South Africa’s mines increased to 88, surpassing the 2016 figure of 73, and ending nine straight years of falling fatalities in a country with an unforgiving geology.