AP

Numbers are up from 36 deaths the year before

Fourth quarter of 2013 saw significant spike compared to rest of year

West Virginia was the state with the most coal mining deaths

RICHMOND, Va. (AP) — Forty-two miners in the United States died on the job in 2013, up from 36 the year before.

The U.S. Department of Labor's Mine Safety and Health Administration released the preliminary data on Monday. It said while the first three quarters of 2013 saw mining deaths occurring at a record-low rate, the fourth quarter saw a significant spike.

Six coal miners and nine metal and nonmetal miners died in accidents during the fourth quarter of last year. That's compared to a total of six miners who died in the same period of 2012.

The state with the most coal mining deaths last year was West Virginia, with six; while the state with the most deaths of metal and nonmetal miners was Kentucky, with four