Ouray Silver Mines, which had almost 200 employees four months ago, has laid off almost all of them, with fewer than 20 remaining. At the same time, the mine’s parent company has received an influx of cash from investors, hoping to resume operations.

Production has stopped while the remaining mine staff focuses on engineering and planning, in the hopes of starting back up later this year.

The changes, including the latest layoffs of about 50 people, are due to ongoing issues related to raise...