(IOCI RADIO) – Illinois now has an official state rock.

The push for naming a state rock came from elementary school students in Naperville and Burr Ridge. They created a list of potential contenders and launched a campaign for for other kids across the state to cast a ballot for their choice.

The winner was dolostone, a type of limestone that makes up the majority of bedrock in Illinois, Rep. Janet Yang-Rohr said.

Students involved in the project wrote letters to lawmakers about their efforts and a few testified in a legislative committee.