Item 1.04 Mine Safety - Reporting of Shutdowns and Patterns of Violations.

On Wednesday, May 19, 2021, at approximately 6:37 a.m., Central Time, an operating subsidiary of U.S. Silica Holdings, Inc. (the "Company"), received an imminent danger order (the "Order") under Section 107(a) of the Federal Mine Safety and Health Act of 1977 (the "Mine Act") issued by the federal Mine Safety and Health Administration ("MSHA"), at the Crane, Texas mine. The Order was issued when a representative of MSHA allegedly observed a contractor truck driver out on the hood of a contractor haul truck attempting to clean the windshield without proper fall equipment. No individuals were injured as a result of the condition alleged in the Order. The driver was safely removed and a citation was issued to the contractor's firm. The Order was then terminated. The Company subsidiary is reviewing MSHA's Order and may seek judicial review of its issuance.

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