On the outskirts of Durban Deep, an abandoned mining town with a labyrinth of underground tunnels long since abandoned by the big gold companies, Elizabeth goes rhythmically about her work.

Grinding piles of rough stones into white, gold-flecked silt on a large concrete slab, the 40-year-old is one of the ghostly dust-covered zama zamas – artisanal miners, mostly illegal – who have turned to scavenging in disused gold and diamond mines across South Africa.

It can be deadly work: more than 24 people died when an abandoned gold mine flooded in neighbouring Zimbabwe in January this year.

Nonetheless, Elizabeth is one of a growing number of women driven into this dangerous world, earning less than £10 a day for crushing up to 20kg of rock retrieved from Johannesburg’s disused mineshafts. The threat of sexual violence is all too common.

“This work is very hard. It’s not a good job,” says Elizabeth, showing her calloused palms. “But in Zimbabwe things are worse, so we have no choice. Now there are more women than before coming to South Africa from Zimbabwe to do this.”

Together with her husband and one of their four children, she came here from Harare in 2015 to search for work. But South Africa has an unemployment rate of 27% and opportunities are scant.

Elizabeth crushes small stones into white, gold-flecked silt. This can cause silicosis, a chronic lung disease. Photograph: Shaun Swingler

According to a 2015 report by the South African Human Rights Commission, the country’s burgeoning illicit gold trade has been fuelled by the formal mining industry’s collapse combined with the failure of the ruling African National Congress to regulate the informal mining sector. Political and economic turmoil in a number of neighbouring countries has only compounded the problem.

The report estimated 30,000 illegal miners were operating across South Africa; about 75% are believed to be undocumented migrants, primarily from Zimbabwe, Mozambique and Lesotho. Hundreds have died due to collapsing mine shafts, gas explosions and turf wars between the criminal syndicates that have seized control of the illegal industry.

On Johannesburg’s outskirts, cut off from support networks and services, women are bearing the brunt of the violence and lawlessness associated with illicit mining.

“Mining is innately male-dominated,” says Kgothatso Nhlengethwa, a Johannesburg-based geologist and researcher on informal mining.

Nhlengethwa says there is a dearth of research on the precarious role of migrant women and the risks and challenges that they face in an industry worth almost £400m a year.

Gang-rape and other forms of sexual violence are common, says Elizabeth. “A lot of women are being raped,” she says. “You hear stories about what happens to them when they go home.”

In December a small group of women marched on the local police station, carrying placards bearing the slogan: “Sick and tired of rape” and demanding greater police protection for the 800-strong community at Durban Deep. Others, though, are simply too afraid to approach the authorities.

Alan Martin, a researcher with the Global Initiative against Transnational Organised Crime, says women have “little negotiating power” with the criminal syndicates in terms of their wages or ability to choose “where to work and what kind of work they do”. Martin says the same applies when they are “shaken down for bribes” by notoriously corrupt police.

Women are frequently coerced into exchanging sexual favours with men, who earn considerably more, in return for a better cut of the takings.

Health is also at risk. “They are crushing a type of rock that is silica based,” Nhlengethwa says. This can cause silicosis, a chronic lung disease that has claimed the lives of thousands of mine workers since the 1960s.

Monica, a 33-year-old Malawian, has been crushing in Durban Deep since she arrived in 2016, working in a small clearing near the mine’s crumbling former staff houses.

“When you are crushing, you often get sick,” she says, fine dust clinging to her skin and clothes as she works. Sometimes, she makes as little as £3 for a full day’s toil.

“It’s small money,” says Monica. “It’s not enough to put food on the table.”

People queue for food parcels at an animal welfare clinic in Durban Deep, Johannesburg. Photograph: Shaun Swingler

On an overcast Saturday morning, a queue of women and small children forms in the car park of the Claw animal welfare clinic, a longstanding institution in Durban Deep. A scheme, run in tandem with the Johannesburg branch of Food Not Bombs, provides free hot meals every Saturday.

“There are at least 80 to 100 women coming every week for food,” says Lara Reddy, Food Not Bombs’ coordinator. “Sometimes it’s much more than that. There’s so much need.”

Claw was founded by Cora Bailey, who has witnessed the steady deterioration of Durban Deep since it ceased formal operations in 2001. Gangs, murders and rape have become commonplace in the sprawling surrounding informal settlements, with the violence so widespread that Bailey claims almost every child here will have witnessed rape or domestic abuse.

With the vast majority of people in the area living off the proceeds of illicit mining, fear of arrest or deportation prevents many women from going to the police or seeking help at overstretched local medical clinics.

“Many of them are undocumented, and there’s a lot of xenophobia towards them,” Bailey says.

Jessica, 30, first moved from the small Zimbabwean town of Lupane to Matholesville, a ramshackle informal settlement about 2km west of Durban Deep, in 2016.

After briefly returning home last year, she returned to Durban Deep in February, pushed by Zimbabwe’s spiralling economic crisis.

“It’s hard to find jobs in South Africa,” says Jessica as she makes her way to work on a busy crushing site behind densely packed rows of corrugated zinc shacks. “This is the only job that I can do because there are no requirements – no passport or ID necessary. All that’s required is my strength.”