NAPERVILLE – Signed into law Monday, legislation by State Senator Laura Ellman and State Representative Janet Yang Rohr on behalf of local students designates Dolostone as Illinois’ official state rock.

“Students played a large part in the designation of our state tree and flower over a century ago, and once again they will play a large part in our state’s history through their work in designating Dolostone as the state rock,” said Ellman (D-Naperville). “These exceptional young people went above and beyond to take advantage of this great learning opportunity, and all the students and teachers involved have been true gems.”

House Bill 4261 was brought to the General Assembly by students from Pleasant Dale School in Burr Ridge and Maplebrook Elementary School in Naperville who discovered Illinois did not have a state rock. The students interviewed regional geology scholars, visited museums and carried research to develop a ballot with three choices. They then asked schools across Illinois to vote on a state rock. Dolostone was the winner.

Dolostone is a sedimentary rock that underlies nearly all of Illinois, with the exception of the northernmost part of the state. It helps enrich soil across the state by providing valuable nutrients for plant growth, and caused a major mineral rush in Galena, Ill. in the early 1800s.

In addition to its natural abundance throughout the state, Dolostone plays a significant role in Illinois through its utilization in many important structures. Most notably, 3,300 exterior dolomite stones were used in the construction of the Old Illinois State Capitol. The quarry the stones were sourced from is now under Lake Springfield.

“I was very happy to join with our community's students and teachers to select Dolostone as Illinois’ official state rock," said State Representative Janet Yang Rohr (D-Naperville), House sponsor of the bill. "Dolostone is the foundation for our former state capitol building, so this is a wonderful way to connect to our state’s past. Working with such a bright group of students served as another reminder that our children deserve the best education possible.”

Dolostone will officially become the state rock of Illinois on Jan. 1, 2023.