Colombia’s ban on mining in highland ecosystems could be a double-edged sword — it may attract illegal miners to the delicate areas where established mining companies cannot operate.

The example of Canada’s Greystar — which last month withdrew permit requests for its gold and silver project over environmental concerns — has crystallized Colombia’s dilemma of trying to balance environmental concerns while boosting investment in its oil and mining sectors.

“That gold will be extracted by someone. It won’t be a company with good practices. It won’t be a company that had eliminated the use of mercury,” said Cesar Diaz, executive director of the Colombian Chamber of Mining.

The fear is that small miners will come into already explored areas with rudimentary techniques that utilize mercury to separate gold and pollute rivers and soil — Colombia has tens of thousands of both legal and illegal miners.