Citizens who have fought a long and, so far, successful battle to prevent the operation of a stone quarry near the rural Montgomery County town of Boyds have won the right to a court hearing that could give them some powerful ammunition in their fight.

The Maryland Court of Appeals, in a ruling issued Monday, said the Boyds Civic Association is entitled to a trial to determine whether proper procedures were used when the county designated that mining was an acceptable land use for a 530-acre tract owned by Rockville Crushed Stone Inc. However, since then, the company has not been able to secure county permission to begin mining on the site.

"We are very gratified. It has taken over 2 1/2 years to acknowledge my client's complaint that what happened in the . . . process was incorrect," said William J. Chen Jr., lawyer for the Boyds Civic Association.

"It's not a big deal," countered Kathleen Sheehy, the attorney for the mining company who expressed confidence that the court will find correct procedures were used.

No matter the outcome of that proceeding, both sides agreed that it will not be the end of the court challenges and zoning ins and outs that have characterized the fight between the residents of the small town, northwest of Gaithersburg, and the company that owns the land, which is rich with stone used to make cement and asphalt.

Rockville Crushed Stone Inc., which also operates the Travilah quarry in the southern central part of the county, has not mined the Boyds land because of county zoning actions. The master plan for the area, drawn in 1978, did not permit mining at that location.

In February 1985, the company convinced the planning board and the County Council to amend the Boyds' master plan to contain a recommendation saying the land is suitable for a Mineral Resource Recovery Zone, the formal name of the classification allowing mining.

It was this action that was flawed, the citizens argued to the state's highest court after lower courts refused to hear their suit. The group contended that the county failed to hold appropriate public hearings and, as a result, the designation of mining as a permissible land use is invalid.

The Court of Appeals, in a unanimous 29-page ruling written by Judge Marvin H. Smith, said the citizens are entitled to a Circuit Court hearing on these issues.

Such action could have important repercussions for the future.

Rockville Stone's land has gone unquarried despite the 1985 master plan amendment because the County Council last June refused to rezone the land to allow mining. It was a hotly contested debate with the hearings spanning 21 days, a county record.

Citizens argued that increased traffic, from big trucks hauling stone, and pollution from the actual mining would adversely affect the town of about 700 people.

Rockville Stone argued that the stone is needed for highway construction in Montgomery County and throughout the state. The firm said that it would haul the mined rock by railroad, instead of trucks, to improve the traffic situation.

The council's unanimous refusal to rezone the land prompted the firm to sue the county, contending the council acted arbitrarily. That case was argued in Circuit Court in April and a decision is pending, but all sides agree an appeal is inevitable.

If the company wins a rezoning through the courts, the issue of whether the master plan was properly amended to make mining a permissible land use becomes all the more important. As the court wrote, "If proper procedures were not followed then there could be no valid plan and hence there could not be Mineral Resource Recovery zoning."

The outcome is also important because of the possibility that Rockville Stone again would try for a rezoning through the council, which has some new members. "So long as the master plan recommends Mineral Resource Recovery zoning for the property of Rockville Crushed Stone," the court wrote, "petitioners face the threat of expensive and time consuming hearings on rezoning applications."

"The threat of such potential rezoning then hangs like a pall of smoke over the properties 'within sight and sound' of the land sought to be quarried," the court concluded.