Sandstone. Sandstone is a sedimentary rock mainly composed of silicate grains, cemented together by another mineral, such as quartz or calcite. It has been quarried and used for construction and art over many millennia.

Sandstone has been quarried in Wilkeson, Washington since the mid 1800’s. According to W.P. Bonney’s History of Pierce County, Wilkeson Sandstone was “pronounced by competent authorities to be superior to any other sandstone in this country” because it did “not absorb water and is so recognized by the United States government in the fact that it is the only sandstone that does not require to be waterproofed.”

In his book, Washington's Audacious State Capital and Its Builders, Norman J. Johnston described Wilkeson Sandstone as "light, warm, off-white tones with shadings of pale cream and hints of pink." On "sunny days," he wrote, "it is light but not harsh, nor does it turn gloomy on gray days or in the rain." Because of these aesthetic qualities and its availability in sufficient amounts, Wilkeson Sandstone was used to grace many buildings in the state, such as Washington's Capitol and Temple of Justice. 

State Symbols. The Washington Legislature has designated several official state symbols, such as a state fruit—apple, state vegetable—Walla Walla sweet onion, state fossil—Columbian mammoth of North America, state waterfall—Palouse Falls, and state gem—petrified wood.

Wilkeson Sandstone is designated as the official sandstone of the state of Washington.