 KATY, Texas, July 15, 2021 PRNewswire -- U.S. Silica Holdings, Inc. NYSE: SLCA announced today that it will release its second quarter 2021 financial results before the New York Stock Exchange opens on Thursday, July 29, 2021. Conference Call This release will be followed by a conference call for investors on Thursday, July 29, 2021 at 8:00 a.m. 