Ndumiso said he normally stayed underground for about three months at a time, and then came up for two to four weeks to spend time with his family and sell his gold, before going back into the deep pits.
"I look forward to sleeping on my bed and eating home-cooked meals. Breathing in fresh air is an amazingly powerful feeling."
Ndumiso does not come out more often in case he loses his digging spot, but after three months it gets too much to remain underground.
He recalled that once when he reached the surface: "I was so blinded by the sunlight that I thought I had gone blind."
His skin had also become so pale that his wife took him for a medical check-up: "I was honest with the doctor about where I lived. He did not say anything, and just treated me. He gave me vitamins."
Above ground Ndumiso does not just relax. He also works with other illegal miners as ore-bearing rocks brought up from below are blasted and crushed into fine powder.
This is then "washed" by his group at a makeshift plant to separate the gold using dangerous chemicals like mercury and sodium cyanide.
Ndumiso said he then sells his share of the gold - one gram for $55, less than the official price of about $77.
He said he has a ready-made buyer, whom he contacts via WhatsApp.
"The first time I met him I did not trust him so I told him to meet me in the car park of a police station. I knew I would be safe there.
"Now we meet in any car park. We have a scale. We weigh the gold on the spot. I then hand it to over to him, and he pays me in cash," he said, pointing out that he walks away with between $3,800 and $5,500.
He gets this amount every three months, meaning his average annual income is between $15,500 and $22,000 - far more than the $2,700 he earned as a legally employed miner.
Ndumiso said the gang leaders earned far more, but he did not know how much.
