Dolomite (also known as dolomite rock, dolostone or dolomitic rock) is a sedimentary carbonate rock that contains a high percentage of the mineral dolomite, CaMg(CO3)2.

CHICAGO — Governor JB Pritzker today joined legislators, students, and teachers at the Morton Arboretum to designate Dolostone as the official rock of the State of Illinois.

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House Bill 4261 began as an initiative led by a group of elementary school students from Pleasantdale Middle School in Burr Ridge and Maplebrook Elementary School in Naperville. After the students discovered that Illinois did not have a state rock, they created a ballot and had students across the state vote for a winner. The chosen rock was Dolostone.

Dolostone, a form of limestone, forms the majority of Illinois’s bedrock, establishing a foundation for the state’s other natural terrain. Its name comes from its original discovery in the Dolomite Alps

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Illinois recognizes several other official symbols of the state, including; state bird- the Northern Red Cardinal, state flower- the violet, state tree- the white oak, and state fish- the bluegill. More officially designated state flora and fauna can be found on the Illinois DNR website.

“Seeing young people use their voices and the democratic process to make change in our state is truly inspiring,” said Governor JB Pritzker. “These young leaders have a bright future of organizing and civic engagement that I am excited to watch. They could not have picked a better rock to represent the strength and stability of Illinois.”

“Students developed and drove this legislation,” said State Senator Laura Ellman (D-Bloomingdale). “It was not only a fantastic learning experience for them, but an opportunity to show others of any age that they have power in Springfield. I encourage Illinoisans to learn more about Dolostone.”

"With today's bill signing, we're not only establishing an official state rock with a long history of economic and geological significance to Illinois, we're building the foundation for a new generation of lifelong learners who are civically engaged and ready to contribute to their communities,” said State Representative Yang Rohr, (D-Naperville).

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