U.S. Silica Holdings Inc.’s (NYSE: SLCA) quarterly profit missed analysts’ estimates on July 31 as its operating expenses nearly doubled.

Total operating expenses of the producer of commercial silica used in the oil and gas industry, jumped 92% to $95 million mostly due one-time charges and costs related to asset impairment.

Revenue from its oil and gas proppants business, its biggest, rose about 38% to $324.1 million in the second quarter.

The business mostly makes frack sand which is used to hold open tiny cracks in shale rocks in order to allow oil and gas to escape.

Net income fell to $17.6 million, or 22 cents per share in the second quarter ended June 30, from $29.5 million, or 36 cents per share, a year earlier.

The drop in profit was mostly due to higher expenses and merger-related expenses.

Excluding items, the company earned 64 cents per share.

Total sales rose 47.2% to $427.4 million.

Analysts were expecting the company to report a profit of 68 cents per share, according to Thomson Reuters I/B/E/S.