A mining company plans to take its fight to overturn the Winona County ban on frac sand mining to the U.S. Supreme Court, a company spokesman said Tuesday.

Minnesota Sands, which lost its case before the Minnesota Supreme Court in March, said the ban violates the U.S. Constitution.

“We are hopeful the Court will decide to hear this case and overturn what we continue to believe is an ordinance that clearly interferes with interstate commerce and violates the Constitution’s Commerce Clause,” company president Rick Frick said in a statement.

The southeast Minnesota county passed the ban in 2016 — the first in the state — after mining of the rich silica sand deposits there had begun.

Frick sued the county in 2017. A district court upheld the ban, as did the Appeals Court in a 2-1 decision in 2018.

In March, the seven-member state Supreme Court affirmed lower court rulings that let the ban stand, with two justices dissenting in full and one dissenting in part.

The ban allows mining for construction sand, a cheaper and less-pure material used on roadways and for other commercial uses. Silica sand is 95% quartz and consists of round, extremely hard granules that prop open cracks in shale rock, allowing the extraction of oil, gas and natural gas liquids.

An organization that fought for the creation of the ban said the company’s appeal to the Supreme Court was “disappointing.”

“The people of Winona County have understood for many years that the frac sand mining, processing and transport industry offers no benefit to rural communities and is too harmful to be allowed to operate in their communities,” said Johanna Rupprecht of the Land Stewardship Project.