Opponents of frac sand mining packed overflow rooms of a committee hearing at the State Capitol Tuesday morning, calling for a two-year moratorium while state regulations are established.

Silica sand is used in hydraulic fracking that extracts natural gas and oil from underground rock, which is becoming big business in North Dakota due to the oil boom.

As sand mines have begun cropping up in Minnesota, many residents are concerned about the impact of mining on the environment.

Several local governments have imposed temporary bans on mining permits, including moratoriums set to expire in southeastern Minnesota counties.

The Star Tribune report the Legislature is weighing a range of regulatory proposals from a statewide moratorium to in-depth environmental reviews or even a tax on frac sand.

Industry representatives tells the Associated Press that mining has created hundreds of jobs and created a way for Minnesota to cash in on the energy boom.