Many of the deep ocean-blue stones are smuggled across the border to Pakistan

Years of war and exploitation have degraded many of Afghanistan's natural resources. But among the still highly prized assets is the lapis lazuli gemstone.

The precious stone has been mined in northern Afghanistan for 6,000 years. But the only pure source is in Sar-i-Sang in the Kocha valley of the country's north.

In video

Al Jazeera's James Bays
meets lapis lazuli miners

To get to the world's largest lapis lazuli mine, you have to go on a gruelling journey.

It takes more than 12 hours from the nearest town by road, although there are no real roads to speak of.

These mountain passes, some extremely treacherous, can be navigated only slowly and extremely carefully.

Finally, you drop down into the Kocha valley - and the mines at Sari-i-Sang, where a village has been built to house the hundreds of men involved in the search for lapis lazuli.

Highly sought

The gemstone - actually a complex mineral made up of sodium and aluminium - has been sought after for thousands of years.

The deep ocean-blue stones are on sale as jewellery and gift boxes in Kabul shops, but much of the lapis mined in northern Afghanistan is smuggled across the border to Pakistan.

The men who work the mines in Kocha valley
get paid only when they find something

The remote village is the base camp for a highly lucrative, yet until recently totally illegal, business.

You are already at a high altitude here - before you start climbing to the mines themselves. At this height you soon get out of breath.

Once inside the dark, airless mineshafts, you meet the men who risk their lives for a tiny share of the profits.

Deep inside the mountain, the only light is from a number of gas lamps. No one is wearing safety equipment as they detonate the dynamite.

Once the dust has settled after a controlled explosion, they go back down the shaft.

Needy families

The men who work in these shafts get paid only when they find something.

Mohammed Habib says he has been working every day for five months and has found nothing. He will stay for another two because his family desperately needs the money.

Back in the 1980s, the proceeds from the mine used to fund the Mujahidin fighting the Soviet occupation. Finding out who takes the profits now is more difficult.

The mine is supposed to be overseen by the Afghan government, but Al Jazeera was told that the government's officials are rarely allowed on site.

Source: Al Jazeera