POSTED: Monday, October 12, 2015 --- 7:18 p.m.

LA CROSSE, Wis. (AP) -- Low oil prices are claiming more Wisconsin sand mining jobs.

U.S. Silica Co. plans to lay off an additional 16 workers at its Sparta processing plant, while Hi Crush Services plans to idle 27 workers at its plant in Augusta. That's according to notices posted Monday by the Wisconsin Department of Workforce Development.

The La Crosse Tribune (http://bit.ly/1LGcyB4 ) reports both companies said falling oil prices had sapped demand for their product, fine-grained sand used in a drilling process known as hydraulic fracturing.

U.S. Silica said in its notice that layoffs would occur in December and could last six months or more. The Hi Crush layoffs are to take effect in November.

In July, U.S. Silica laid off 30 workers, leaving a staff of 34 at the Sparta plant.

Copyright 2015: Associated Press