The mine has the king's blessing but no environmental authorisation.

The sound of hydraulic rock breakers at work, hacking great chunks from the face of some of the oldest mountains in the world, can be heard echoing down the Mgwayiza Valley in Eswatini.

For over a year now, Michael Lee Enterprises (registered in Eswatini), a company with the same name as its Taiwanese owner, has been mining green chert from outcrops within Malolotja Nature Reserve.

The cryptocrystalline quartz is sent to a sorting site above the Nkomazi River, loaded into shipping containers and trucked to a railway dry port in Matsapha, the kingdom's primary industrial town. According to the truck drivers, the green chert is then railed to Maputo in Mozambique, where it is exported.

"I take two to three full loads of green stone a day to the Matsapha railways," a driver told GroundUp.

His truck had broken down on the highway. Its burnt-out brake discs were steaming. "Normally my truck should hold 25 tonnes, but today they have loaded me with 37. This is dangerous for the truck, and for me."

According to the drivers and also loading workers, there are four to eight collections with 40-foot shipping containers daily.

People living nearby, environmentalists and some tourism industry...