A Colorado canyon consisting of sedimentary rock layers left by an ancient ocean.
Colorado has a fascinating geological history. Ancient oceans intermittently flooded the state over millions of years, leaving bright sandstone and intricately carved canyons. Magma rose to the surface under great pressure and formed dramatic mountain ridges. You can easily find evidence of this rich geological past by collecting stones while walking or hiking through Colorado's canyons or mountains. Colorado's best-known stones include granite, sandstone, marble and jasper.
Granite
Granite is an igneous rock, meaning that it forms from crystallized volcanic magma. Colorado's granite is approximately 1.7 billion years old. It occurs in attractive pastel shades of grey, pink and tan, with veins of white quartz, black mica, green feldspar and silver-gold muscovite. Chunks of granite lie strewn about the Colorado Rocky Mountains and canyons, catching the sun with their sparkling mineral veins. Many Colorado landscaping businesses sell native granite.
Sandstone
Sandstone is a sedimentary rock, which means it forms from pressurized layers of mud, gravel and sand deposited by a body of water. It's abundant in Colorado, due to the state's repeated flooding by prehistoric oceans. Famous Colorado sandstone deposits -- like the Lyons Sandstone, Red Rocks and the Flatirons outside of Boulder -- formed approximately 260 to 300 million years ago. Colorado sandstone is famous for its tan, orange, pink and deep red colors; the shade depends on the amount of iron oxides present.
Marble
Marble is a metamorphic rock, which means it formed from another type of rock that underwent extreme pressure and heat. In the case of marble, the original rock is limestone. Colorado's marble is approximately 1.7 billion years old. The town of Marble, Colorado has been famous since the 1800s for its marble quarries. The tomb of the Unknown Soldier was created from a 100-ton block of pure white marble found in the Yule Marble Quarry outside of Marble. Other quarries around the town produced some of the marble used in the Lincoln Memorial.
Jasper
Jasper is a type of chalcedony, which in turn is a type of quartz. Quartz can be igneous, metamorphic or sedimentary. Arrowheads and primitive tools fashioned by ancient Indian tribes often consist of jasper. The Indians also used the stone's sharp, hard edges to shape other materials. Jasper occurs in many colors and combinations of colors, which makes it a popular ornamental gemstone. In Colorado, shades of yellow, red and orange jasper are common.
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