China clay company Imerys has announced 70 workers are to lose their jobs.
The company said the job cuts were a result of a restructure within its mid-Cornwall operations in the St Austell area.
The French-owned firm said its aim was to secure the long-term future of the china clay industry in Cornwall.
More than 60 jobs were axed last April, with others relocating from the company's laboratories in St Austell to Heathfield in Devon.
In a statement, the company said: “Imerys very much regrets that it is necessary to take these actions and recognises that this is a difficult time for all its employees.
“Every effort will be made to achieve the proposed reductions through voluntary redundancy but compulsory redundancies may also be necessary.’’
St Austell and Newquay MP Stephen Gilbert said the loses would be devastating for the families of those affected.
He said: “Any job loss is devastating for the individuals and families concerned and I will be working closely with Imerys and local support agencies to make sure that individuals are able to access help to find new work as quickly as possible.”