“Of the eight coal mining deaths, two miners died in accidents involving machinery, two in powered haulage, two in a fall of rib/face, one in a fall of roof, and one in falling material,” the US Department of Labor’s Mine Safety and Health Administration said.

There were also two fatalities in surface coal mines, eight in surface hard rock mines and two in underground hard rock mines.

MSHA said half of the non-coal deaths – five in total – occurred at small mines with fewer than 10 employees.

While there were eight coal fatalities in the first halves of 2014 and 2015, there were an additional four non-coal mining deaths in the recent half.

The youngest coal fatality was of a 29-year-old roofbolter who was struck by a falling rock.

“Mining fatalities are preventable, and each of these deaths reminds us that much more needs to be done to protect the nation’s miners,” MSHA chief Joseph Main said.

“Safe mine operation must be at the forefront at all times to avoid the pain and suffering the families of these miners now have to endure.”