Colorado’s State Rock Has a Surprising Origin

If you have ever visited the Colorado State Capitol or seen photos of the Lincoln Memorial, then you have laid eyes on Colorado’s official state rock. Yup, just like we have a state flower or a state bird, Colorado has a state rock.

Known as Yule Creek Valley marble, or Yule Marble, it comes from a small town in Gunnison County. Keep scrolling to find out more about why Yule Marble is Colorado’s rock that rocks, and how you can see it being mined for yourself.

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Meet Colorado’s Official State Rock: Yule Marble

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The Centennial State selected our official rock back in 2004, with a little help from Girl Scout Troop 357. Yule Marble is nearly 99.5% pure calcite, which gives the rock its bright white color and smooth texture that architects love. The quarry in Marble, Colorado, sits at nearly 9000 feet, which means not only is it hard to find, but it's also hard to mine, and it's hard to bring it back down the mountain once you have it.

Yule Marble, Explained in Plain English — and Where You’ve Seen It

Did you know that Yule Marble starts as limestone? Heat and pressure squeeze and recrystallize the rock into the dense, polish-friendly stone Colorado calls marble. Our marble gained fame when it was used in the Lincoln Memorial, the Washington Monument, and the Tomb of the Unknown Soldier in Washington, D.C. Here at home, it was used to build the state capitol in Denver.

The Girl Scout Project That Made History

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How did the Girl Scouts help with all of this? Colorado Troop 357 was lobbying lawmakers in 2004 to complete Colorado’s red, white, and blue trio of state mineral symbols. Thanks to Troop 357, Yule Marble was designated as the state rock, and the Girl Scouts are part of that statewide legacy.