Environmental Roadblocks Mount for Aclara’s Rare Earth Project in Penco
The Penco rare earth project, developed by Aclara Resources—a subsidiary of Canada’s Hochschild Mining—enters a new phase of uncertainty as environmental scrutiny intensifies.
This Tuesday, Chile’s Environmental Evaluation Service (SEA) delivered the ICSARA report (Consolidated Report of Clarifications, Rectifications, or Expansions) to Aclara, compiling feedback from more than 15 public agencies on the project’s latest environmental addendum.
The new round of observations casts fresh doubt on the environmental viability of the project. Longstanding concerns regarding biodiversity, land use, and heritage have resurfaced, along with more technical and rarely raised issues.
A Flagship, Yet Troubled, Project
Aclara seeks to develop a processing plant for ionic clays in Penco, in the Biobío region. With a proposed investment exceeding US$130 million, the plant is expected to yield around 1,700 metric tons of rare earth concentrate per year—enough to supply materials for roughly one million electric vehicles annually.
Currently, it is the only rare earth mining project under environmental review in Chile, making it a bellwether case for the future of the industry in the country.
Return of the “Naranjillo” Issue
One of the most critical agencies in this round was the National Forestry Corporation (CONAF), which revived concerns that derailed previous versions of the project.
CONAF raised alarms over the impact on Citronella mucronata (naranjillo), a native and protected plant species. In April 2025, its field teams identified 34 adult and 2 juvenile specimens within the project’s footprint.
CONAF also demanded stricter plans to control invasive species such as Scotch broom, blackberries, and acacia. Additionally, it criticized the lack of traceability regarding the germplasm intended for revegetation efforts.
Weak Flora and Fauna Data
The SEA report also criticized the baseline environmental data submitted by Aclara. Sampling stations for fauna were mislocated or overlapped different habitats, while flora data included unjustified changes to forest boundaries and errors in classification of native vegetation.
Cultural Heritage Concerns
The National Monuments Council (CMN) objected to the lack of archaeological assessment in previously used forestry areas. They requested evaluations even in areas without visible findings, citing potential for subsurface remains.
Local Government Pushback
The Municipality of Penco criticized the project’s socio-territorial characterization, especially the exclusion of areas like Cosmito and Santa Rosa. The SEA has asked Aclara to include georeferenced and primary data for these zones.
Technical Deficiencies in Key Areas
The General Water Directorate (DGA) and the Environmental Superintendency (SMA) demanded improvements in water monitoring and management of treated effluents. Air quality assessments were also found lacking in updated data and modeling.
What’s Next for Aclara
Aclara must now respond to the ICSARA with a new addendum. The environmental review process is suspended until then. With objections from 15 regulatory bodies, the project’s path forward remains steep and uncertain.