The men in ragged clothes, many barefoot and covered in grime, scramble deep into the earth, searching for veins of a blue-green stone believed to exist only in the southwestern mountains of the Dominican Republic.
The stone is larimar, and its existence under these wooded slopes has been both a boon and a curse for men such as Juan Pablo Feliz, who says there is no other work in the impoverished region. Few strike it rich, but the gem has provided modest incomes for about 1,000 miners and their families since they began working the deposits four decades ago.
Now, Dominican officials are trying to make mining safer and more profitable for the men, who toil in roughly five dozen makeshift tunnels that pockmark the forested mountains of Barahona province like ugly scars.
In March, authorities celebrated the completion of a 400-meter (400-yard) tunnel meant to make the work safer. And the government opened a school last fall to train locals to cut and polish larimar and turn it into jewelry, hoping to increase their meager income.
Prices for larimar jewelry can vary from a few dollars for a bauble sold on a Dominican beach to thousands of dollars in an upscale store or abroad.
"The idea is to give some added value to the stone, and to see that value stay in this region," said Brunildo Espinosa, director of the school, which now has 130 students whose works will be sold at a state-sponsored store in the Punta Cana resort complex and in the capital, Santo Domingo.
The new projects are part of the government's efforts to promote tourism in Barahona and neighboring Pedernales province, which share some of the most beautiful seascapes of the country, including the pristine Bahia de las Aguilas.
The view of the Caribbean from the mountains where miners toil inspired the stone's name — "mar," coming from the Spanish word for sea, and "lari," from "Larissa," the name of the daughter of local craftsman Miguel Mendez. He is the man who found the larimar deposits in 1974 with help from Norman Rilling, a geologist who was in the Dominican Republic as a Peace Corps volunteer.
"It was a big deal," Mendez told The Associated Press. "It was the only new thing to happen for local crafts."
Mendez recently reopened a crafts shop in Santo Domingo to create sophisticated designs with the colorful stone. He said demand is also strong in China, India and Russia, but he hopes the opening of the local jewelry school may help keep more larimar in the Dominican Republic, meaning greater profits for the local community.
"The country has had a shortage of good jewelers. The school is a good start," he said.
State involvement in the mines grew out of the bleak conditions underground and a pair of deadly accidents. In 2006, four workers died from asphyxiation, and two others were lost in 2013.
The mines can run as deep as 120 meters (395 feet). Mud-covered men squirm through tight spaces in suffocating heat with only a string of dim light bulbs in some parts of the passages. There are no helmets or protective goggles in sight.
Wooden support planks protect the miners from collapse, and snaking lines of perforated tubes deliver oxygen to them as they dig underground. Even these innovations are relatively recent, workers say.
"Of course there's risk, but there's no other work, so you have to do it," Feliz said as he repaired a ventilator needed to supply oxygen to a dozen men waiting to dig 60 meters below ground.
The new tunnel is intended to provide safer working conditions in the mines and some order to the chaotic sector. It was built with European Union aid at a cost of 200 million pesos ($5 million), including construction of a local road and school.
The tunnel, which will be open for use in April, will also help miners reach more significant veins of larimar, said Jose Gomez, vice president of one mining cooperative.
The local mining cooperatives have held the right to dig since the early 1980s. They don't pay taxes and there are no official statistics about the economic impact of this growing informal industry.
But for the miners, digging for larimar is worth the risk.
Local men who want to start mining typically group together and then seek an investor willing to pay for the necessary equipment and fuel. Miner Anibal Franquis said he has saved enough in his 23 years of digging to become an investor, putting up $40,000 at a time to sponsor an excavation project.
"It's like a lottery: You never know what you are going to get," Franquis said. "Sometimes months pass when you get nothing. But there are years when it gives you millions [of pesos]."
The miners welcome the new efforts to boost their product.
Luis Antonio Gonzalez, a former professional baseball player whose career included stints in the U.S. minor leagues, now invests in the cooperatives but says everyone could benefit from more promotion.
"The world should know that the only place in the world where there is larimar," he said, "is in the Dominican Republic."