There have been allegations that the mine's operations have caused heavy metal pollution affecting especially local indigenous Zenu and Afro-Descendant residents.

In March 2018 a Review Chamber of the Constitutional Court of Colombia ordered Cerro Matoso to pay damages to local communities.

[3] It developed over a Cretaceous peridotitic protolith,[3] which is exposed in the form of an isolated elongated hill covering an area of about 4 square kilometres (1.5 sq mi).

These veins contain the distinctive green mineral known as garnierite (actually pimelite, a form of nickeliferous talc) as well as quartz and chalcedony, and they can have a Ni content of up to 30% to 40%.

[9] With exploration rights over 77,000 hectares (190,000 acres) in the main part of the Colombian nickel belt, Cerro Matoso has mining concessions containing reserves capable of sustaining the current[when?]

Local indigenous Zenu residents have complained for decades about adverse health effects, such as an increase in neoplasms and respiratory, dermatological, ocular, and reproductive problems.

However, the alleged responsibility of Cerro Matoso for health problems suffered by members of the surrounding communities is rejected by the company on the basis of the evidence available.

The most recent air quality study was carried out by the Regional Environmental Corporation (a Colombian state agency) in 2016 and revealed “optimal conditions” in relation to the measurements of all the pollutants criteria and their permitted levels.

It reported that people living up to 15 km away from Cerro Matoso commonly had a high frequency of skin lesions and upper respiratory tract irritation.

[16][17] The experts noted that the study documented several general health factors in the local communities which correlate with their epidemiological profile, such as the lack of drinking water, firewood cooking, garbage burning, or the existence of unpaved roads.

[18] In March 2018, the 7th Review Chamber of the Constitutional Court of Colombia sided with local residents and ordered the mine to pay for damages.