CO 220px-Map of USA CO

Rockhounding Colorado

Colorado is an extraordinary state for rockhounding.  The state is famous for silver and gold mines.  Colorado also has numerous fossils sites, including fabulous dinosaur sites and tracksites as well as petrified wood.  In addition, Colorado has an amazing variety of minerals and gemstones, including its famous well crystalized amazonite and smoky quartz specimens.  Dozens of meteorites have been found in the state.  Colorado also is home to several astonishing state and national parks and monuments.

State Rocks, Gemstones, Minerals, Fossils, & Dinosaurs

Rockhounding Tip:  Knowing state rocks, gemstones, minerals, fossils, and dinosaurs often can be very useful information for rockhounders.  Ordinarily, states with significant mineral deposits, valuable gemstones, fossils, or unusual or significant rock occurrences will designate an official state mineral, rock/stone, gemstone, fossil, or dinosaur to promote interest in the state’s natural resources, history, tourism, etc.  Accordingly, such state symbols often are a valuable clue as to potential worthwhile rockhounding opportunities.

Colorado - Rock Yule Marble  Yule Quarry  CO 1A

Yule Marble

State Rock:  Yule Marble (2004)

Colorado designated yule marble as its official state rock in 2004.  Yule marble is a type of metamorphosed limestone found only in the Yule Creek Valley in the West Elk Mountains of Colorado (south of the town of Marble, Colorado).  The marble was created by heat from an igneous intrusion that metamorphosed the Leadville Limestone along Yule Creek into white, crystalline marble.  This white marble is comprised of almost pure calcite grains tightly joined to give it a luminous quality.  Yule marble is famed for its purity and uniform whiteness.  The marble deposit was reported in the late 1800s in Gunnison County on Yule Creek although a producing quarry did not begin operations there until 1906.   The outstanding quality of the yule marble made it the choice for use in the basement of the Colorado Capitol as well as numerous buildings and monuments in the United States including the exterior of the Lincoln Memorial and the Tomb of the Unknown Soldier (which used a 56-ton block of Yule marble).


Colorado - gem Aquamarine1


State Gemstone:  Aquamarine (1971)

Colorado designated aquamarine as its official state gemstone in 1971.  Aquamarine is the pale blue, and deep blue to blue-green, variety of the mineral beryl (the deep green variety of beryl is the gem emerald).  Colorado is one of the major producers of aquamarine in the United States.  The mountain peaks of Mount Antero and White Mountain in Chaffee County, Colorado are among the finest quality localities known for gem aquamarine.  They are also among the highest in elevation, located at 14,000 feet. The granite rock of these peaks contains pegmatite bodies that are characterized by large cavities containing the gem quality aquamarine crystals.  The cavities are found through a vertical area of a mere 500 feet.  The crystals in these cavities range in color from light blue to pale and deep aquamarine green, and in size from very small to 6 cm in  length.  Aquamarine was first discovered in pegmatite pockets on Mount Antero in 1881. 


Colorado - Mineral rhodo


State Mineral:  Rhodochrosite (2002)

Colorado designated rhodochrosite as its official state mineral in 2002.  Rhodochrosite is a deep red to rose pink manganese carbonate mineral found in eighteen of Colorado's counties associated with gold, silver, lead, zinc, and molybdenum ores.  Rhodochrosite's common crystal habit is the rhombohedrum typical of carbonate minerals.  It is also found in Colorado as massive, dogtooth, disc like, radiating, granular, stalactitic, and rosette forms.  While there was some debate as to whether the state mineral should be gold or silver or another mined mineral historically associated with Colorado, it was decided that rhodochrosite is associated internationally with the state more than any other mineral.  The world's largest rhodochrosite crystal, called the Alma King, is on display at the Denver Museum of Nature and Science. It was found in the Sweet Home Mine near Alma (Park County), Colorado.  Although rhodochrosite is most commonly pink and opaque, Colorado's translucent red variety is prized the world over.


Colorado - fossil Stegosaurus at DMNS


State Fossil:  Stegosaurus stenops (1982)

Colorado designated Stegosaurus as its official state fossil in 1982.  Stegosaurus was about 25 feet long and eight feet high and was characterized by its plates and spikes.  Although the average Stegosaurus may have weighed 3.5 tons, its brain was only the size of a walnut.  The Stegosaurus lived in the area we now know as Colorado 150 million years ago during the Mesozoic era in the Jurassic period. 
 The first Stegosaurus skeleton was found just west of Denver in 1877.  Over a century later, a nearly complete, articulated specimen was found near Canon City and is now on display at the Denver Museum of Nature and Science.  Many other specimens were found in the world-famous Morrison Formation, named for the town of Morrison, Colorado.


Rockhounding Resources

State-specific rockhounding books (including the books listed here as well as other books), regional rockhounding site guides, and other helpful rockhounding resources are identified - by category - in the Books & Gear section of Gator Girl Rocks with a link to the Gator Girl Rocks Amazon Store where you may easily browse selected resources and securely place an order.  Your order will benefit Charity Rocks!

Geologial Survey logo - CO

Colorado Geological Survey
One of the better state geological survey websites.


BLM Colorado

U.S. Bureau of Land Management – Colorado
The BLM manages 8.4 million acres of federal public lands in Colorado.


Western Paleo logo

Western Interior Paleontological Society

Colorado Meteorite Society

Colorado Cave Survey

  • Halka Chronic & Felicie Williams, Roadside Geology of Colorado (2002).
  • James R. Mitchell, Gem Trails of Colorado (2d ed. 2008).
  • William A. & Cora Kappelle, Rockhounding Colorado (2d ed. 2004).
  • Stephen M. Voynick, Colorado Rockhounding: A Guide to Minerals, Gemstones, & Fossils (Rev. ed. 1995).
  • Richard M. Pearl, Colorado Gem Trails & Mineral Guide (3d ed. 1972).
  • Herbert W. Meyer, Fossils of the Florissant, (2003).
  • John T. Jenkins & Janice L. Jenkins, Colorado’s Dinosaurs (1993).
  • Dougal Dixon, Camarasaurus and Other Dinosaurs of the Garden park Digs in Colorado (2008). 
  • David Harris, Colorado Caves: Hidden Worlds Beneath the Peaks (2001). 
  • Mathew L. Morgan, The Handbook of Colorado Meteorites (2000).
  • Allan W. Eckert, Earth Treasures Vol. 4A - Southwestern Quadrant (1987; reprint in 2000).
  • James Martin Monaco & Jeannette Hathway Monaco, Fee Mining & Rockhounding Adventures in the West (2d ed. 2007). 
  • Kathy J. Rygle & Stephen F. Pedersen, Southwest Treasure Hunter's Gem & Mineral Guide (4th ed. 2008).


Museums of Interest to Rockhounders

Museum - DenverMuseumNatureScience

Denver Museum of Nature & Science
Denver, Colorado
Formerly named the Denver Museum of Natural History, the museum's collections include fossils, rocks, meteorites, gemstones, and minerals.  The museum's specimens include a 13 pound gold nugget found in 1887 as well as the 'Alma King,' a four-inch rhodochrosite crystal.


Museum - Leadville National Mining

National Mining Hall of Fame & Museum

National Mining Hall of Fame & Museum
Leadville, Colorado
Located in the famous 1880's silver mining boomtown, the National Mining Hall of Fame & Museum is a monument to the memory of the men and women who pioneered the discovery, development, and processing of our nation's natural resources.


Museum CO School of MInes Geology Museum

Colorado School of Mines - Geology Museum

Colorado School of Mines Geology Museum
Golden, Colorado
The Colorado School of Mines Geology Museum, started in 1874 by Arthur Lake, exhibits minerals, fossils, gemstones, meteorites, and historic mining artifacts.  The museum includes minerals from Colorado as well as other localities.  The meteorite collection includes over 200 specimens.  In addition, the museum exhibits one of the ‘goodwill moon rocks’ collected during the Apollo 17 lunar mission.



Museum - Morison Natural History Museum Logo

Morrison Natural History Museum
Morrison, Colorado
The Morrison Natural History Museum, located near the world famous Morrison Formation, provides a glimpse of the first important dinosaur discoveries in Colorado including fossils from the first Stegosaurus and Apatosaurus ever discovered.


Museum - Dino Journey Logo

Museum of Western Colorado’s Dinosaur Journey Museum
Fruita, Colorado
Dinosaur Journey tells the story of the history of life in western Colorado and surrounding areas with real fossils, cast skeletons and robotic reconstructions of dinosaurs.  The hands-on, interactive museum includes paleontology displays and a working laboratory where dinosaur bones are prepared for display.


Museum - Dino Depot Logo

Dinosaur Depot Museum
Cañon City, Colorado
The Dinosaur Depot Museum exhibits dinosaur fossils from the Garden Park Fossil Area, which has produced world-class Late Jurassic fossils since 1887.  The Garden Park Fossil Area has produced some of best dinosaur fossils found anywhere, including three articulated skeletons of Stegosaurus stenops.  The first was found in 1886 and is in the National Museum of Natural History in Washington, DC.  The second was found in 1937 and is in the Denver Museum of Nature and Science.  The third, the world's most complete, was removed from Garden Park in 1992 and the largest jacket weighing over 13,000 pounds was brought to the Dinosaur Depot Laboratory for preparation.  A full-size replica of this stegosaurus is on display in the Museum.  The museum includes an active laboratory where visitors can view the preparation of fossils.


University of Colorado Museum of Natural History
University of Colorado – Boulder, Colorado
The museum’s Paleontology Hall features fossils that can be touched, seen, and felt, including petrified woods, giant fossil clams, and a dinosaur footprint.


Museum - RMDRC

Rocky Mountain Dinosaur Research Center

Rocky Mountain Dinosaur Resource Center
Woodland Park, Colorado
The Rocky Mountain Dinosaur Resource Center exhibits dinosaurs and other fossils.  It also includes a fossil preparation lab.



Places to Visit - Interesting Sites To See

Site - Dino National Monument - Zoe & SIgn
SIte - Dino National Monument - Zoe & Bone

An excavated dinosaur bone … and me in 2009

Dinosaur National Monument
Colorado & Utah
Dinosaur National Monument protects a large deposit of fossil bones of creatures that lived nearly 150 million years ago.  The rock layer enclosing the fossils is a sandstone and conglomerate bed of alluvial or river bed origin known as the Morrison Formation from the Jurassic Period 150 million years ago.  The dinosaurs and other ancient animals were washed into the area and buried presumably during flooding events.  The pile of sediments were later buried and lithified into solid rock.  The layers of rock were later uplifted and tilted to their present angle by the mountain building forces that formed the Uinta Mountains.  This site provides one of the best snapshots of Jurassic dinosaurs found anywhere in the world.


Site - Florissant Fossil Beds NM

Florissant Fossil Beds National Monument
Teller County, Colorado
Florissant Fossil Beds National Monument includes one of the richest and most diverse Eocene fossil deposits in the world.  The site includes huge petrified redwood stumps up to 14 feet wide and thousands of detailed fossils of insects and plants.  Almost 35 million years ago, enormous volcanic eruptions — now designated the Thirty-nine Mile volcanic area – buried the then-lush valley and petrified the redwood trees that grew there.  A lake formed in the valley, and the fine-grained sediments became the final resting-place for thousands of insects and plants.  These sediments compacted into layers of shale and preserved the delicate details of these organisms as fossils.


Site dinosaur-ridge sign

Dinosaur Ridge
Morrison, Colorado
Dinosaur Ridge is part of the Morrison-Golden Fossil Areas National Natural Landmark.


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Me at Dinosaur Ridge in 2005

Dinosaur Ridge Trail
Morrison, Colorado
The Dinosaur Ridge Trail is 1.5-mile trail along Alameda Parkway, between Rooney Road North and County Road 93.  West Alameda Parkway traverses the Dakota Hogback, which has locally been renamed “Dinosaur Ridge” by the USGS.  The National Park Service has designated the area a National Natural Landmark.  Along the Trail, there are over 15 sites, each marked by an interpretive sign.  The sites include hundreds of dinosaur tracks, a quarry of dinosaur bones, interesting geologic features, and scenic overlooks of Colorado’s Front Range


SIte - Dino Ridge Tracksite

Dinosaur Tracksite - Dinosaur Ridge

Dinosaur Tracksite
Morrison, Colorado
The Dinosaur Tracksite was uncovered during the construction of West Alameda Parkway in 1937.  Today, after an expansion of the main site in 1994, over 300 early Cretaceous Period dinosaur tracks have been identified.  Of those at least half are periodically colored using charcoal by Dinosaur Ridge volunteers to help visitors see the tracks in the sandstone.  The tracks are those of Iguanodon-like plant-eating dinosaurs and ostrich-sized meat-eating dinosaurs.  These tracks represent only a small part of the extensive track-bearing beds of the Dakota Group that can be traced from Boulder, Colorado to northern New Mexico.  Because these strata represent the shoreline sediments of an ancient seaway that was frequently trampled by dinosaurs, these beds have been called the "Dinosaur Freeway."


Site - Dino Ridge Quarry Article smithsonian morrison quarry

Dinosaur Ridge Bone Quarry
Morrison, Colorado
Arthur Lakes, a professor at the Colorado School of Mines, discovered the Late Jurassic ‘Dinosaur Ridge Bone Site’ in 1877.  It was referred to as Morrison Quarry Number Five (of the 14 quarries in the area, only four actually produced dinosaur fossils – Nos. 1, 5, 8, and 10).  The world’s first Stegosaurus was discovered at Quarry Number Five (several vertebrae, parts of limbs, and pieces of the famous plates were uncovered and are exhibited at the Morrison Natural History Museum).  The bones exposed today at the interpretive site are most likely from Stegosaurus and Apatosaurus, which existed about 150 million years ago, and washed into this small braided stream channel deposit during a flooding event.  The Bone Quarry is one of a few locations where you can see and touch fossilized dinosaur bones in place.


Site - Picketwire Tracksite

Picketwire Tracksite

Picketwire Canyonlands Dinosaur Tracksite

Comanche National Grassland – Southeastern Colorado

This is the largest dinosaur tracksite in North America.  It is located in Picket Wire Canyon on the banks of the Purgatoire River on federal public lands managed by the US Forest Service in the Comanche National Grassland in southeast Colorado approximately twenty miles south of La Junta, in Otero County, Colorado.  The tracksite, which occurs in limestone of the Jurassic Morrison Formation, is the largest documented assemblage of trackways in North America.  Over 1,400 prints in 100 separate trackways extend across a quarter mile expanse of bedrock.  The tracks include both biped and quadruped dinosaurs.  About 150 millions years ago, southeastern Colorado was dominated by a vast freshwater lake.  As the dinosaurs plodded through the mud along the edge of this lake, they left behind vast trails of footprints.  Later, these muddy flats were buried and turned to stone.  The tracksite is far from paved roads, but accessible by hiking on foot, by mountain bike, or by horseback.  The US Forest Service also conducts vehicle access tours.


Site - BLM Garden Park Fossil Area - Marsh Quarry 1888

Marsh Quarry - 1888 - at the Garden park Fossil Area

Garden Park Fossil Area
Near Cañon City, Colorado
The Garden Park Fossil Area is located on federal public lands managed by the Bureau of Land Management.  The Garden Park Fossil Area is one of the most productive and historically important areas in the western United States for the understanding of Late Jurassic dinosaur faunas. The Garden Park area is one of the few places in the Western United States where dinosaur remains occur from bottom to top of the Morrison Formation. They have been collected from no fewer than 25 quarries in the Garden Park area, which is the “type locality” of many species of famous dinosaurs, including species of Allosaurus, Camarasaurus, Diplodocus, and Stegosaurus.  Two roadside stops occur near two of the historic quarries in the area. The Cleveland Quarry (also known as the Delfs Quarry, named for Edwin Delfs, who excavated the quarry for the Cleveland Museum of Natural History between 1954 and 1957 was across Four-mile Creek near the valley bottom and produced one of the most complete known skeletons of the primitive long-necked sauropod, Haplocanthosaurus delftsi.  The skeleton is the only mounted specimen of this genus and is on display at the Cleveland Museum of Natural History in Ohio.  The Marsh-Felch Quarry (0.2 mile north of the Cleveland Quarry) has a quarter mile long hiking trail to an overlook of the Marsh-Felch Quarry. The Marsh-Felch Quarry is the type locality for a number of dinosaur species, including Allosaurus, Ceratosaurus, Diplodocus, Haplocanthosaurus, Labrosaurus, Morosaurus, and Stegosaurus.  The bones of 65 individual dinosaurs were found in this quarry.


Site - Pikes Peak

Pikes Peak

Pikes Peak
West of Colorado Springs, Colorado
Pikes Peak is approximately ten miles west of Colorado Springs.  It is not a volcano and has never been one.  The granite rock of which the mountain is made was once hot molten rock located as deep as 20 miles beneath the earth's surface.  The molten rock hardened and cooled below the earth's surface as much as one billion years ago.  Great forces within the earth's crust pushed the rocks upward through a process called uplifting which created a dome-shaped mountain covered with a thick layer of soil and softer rock.  Erosion and weathering loosened the softer layers and carried them away.  After hundreds of thousands of years of erosion and weathering, a tall granite mountain lay exposed like a large piece of stone waiting for the sculptor to shape it.  Anyone seeing this ancient mountain would not have recognized it as the mountain we know today as Pikes Peak. It took the movement of huge glaciers that once existed on the peak to sculpt the mountain.  The glaciers lasted about one million years and that ice age ended around 11,000 years ago.  Acting like a giant cookie cutter, the powerful bodies of ice gouged out the rock and left deep, straight-walled basins like the Bottomless Pit with its sharp drop of 1700 feet.  The flowing “rivers of ice” carved the U-shaped canyons that lead down Pikes Peak.  Other v-shaped valleys owe their existence to ordinary streams.


Site - Great Sand Dunes

Great Sand Dunes National Park

Great Sand Dunes National Park & Preserve
Mosca, Colorado

The Great Sand Dunes National Park and Preserve, located in the easternmost parts of Alamosa and Saguache Counties, Colorado, protects the tallest sand dunes in North America.


Site - Rocky Mountain National Park

Rocky Mountain National Park

North Central Colorado
Rocky Mountain National Park, split by the continental divide, includes 60 mountain peaks over 12,000 feet above sea level.  We visited in 2004.


Site - Mesa Verde NP

Mesa Verde National Park

Mesa Verde National Park
Southeastern Colorado
Mesa Verde National park is located in southeastern Colorado near the ‘four corners.’  Mesa Verde, Spanish for green table, features numerous ruins of villages and homes built by the Ancestral Puebloan people (Anasazi) who made it their home for over 700 years, from about A.D. 600 to A.D. 1300.


Site - Garden of the Gods

Garden of the Gods
Colorado Springs, Colorado
The Garden of the Gods Park is a Registered National Natural Landmark and public park in Colorado Springs, Colorado.  The outstanding geologic features of the park are the ancient sedimentary beds of red, blue, purple, and white sandstones, conglomerates, and limestones that were deposited horizontally, but have now been tilted vertically and faulted by the immense mountain building forces caused by the uplift of the Pikes Peak massif.  The Park includes an informative Visitor's Center. 
 We visited in 2005.


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Me at the Garden of the Gods in 2005

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Dad and me at the Garden of the Gods in 2005

Site - Red Rocks VC

Red Rocks Visitors Center

Red Rocks

West of Denver, Colorado
Red Rocks is a geologically formed, open-air amphitheater that is not duplicated anywhere in the world.  The design of the Amphitheatre consists of two, three hundred-foot monoliths (Ship Rock and Creation Rock) that provide acoustic perfection for any performance.  There is an informative Visitor's Center.
  We visited in 2005.

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Me and mom at Red Rocks in 2005


Site - Yule Marble Mine

Trail near Yule Marble Mine

Yule Marble Quarry
Marble, Colorado
The Yule Marble Quarry Hiking Trail, outside Marble, Colorado, provides views of large blocks of scrap marble (that contained fractures or flaws).


Site - Royal Gorge Bridge

Royal Gorge

Royal Gorge
Cañon City, Colorado
The Royal Gorge (sometimes referred to as the Grand Canyon of the Arkansas River) is a deep, narrow canyon on the Arkansas River that cuts through the granite of Fremont Peak.  The canyon is about 1,250 feet deep.


Site - Lamar PW Gas Station

Petrified Wood Building

Petrified Wood Building
Lamar, Colorado
Lamar's Petrified Wood building started out as a gas station, built by lumber dealer W.G. Brown in 1933.  The building walls and floors are constructed of large pieces of petrified wood over 175 million years old. 

Site - Granada Flagpole

Granada Flagpole
Granada, Colorado
The base of the flagpole includes rocks from all fifty states.


Rockhounding Sites for Children & Families

Specimen - Rhodochrosite - Alma King rhodochrosite

The 'Alma King' rhodochrosite specimen

Colorado has extensive rock, mineral, gemstone, and fossils sites.  Many individual sites are well known to rockhounders worldwide.  In addition, broad areas of Colorado are known for particular specimens – for example, aquamarine at Mt Antero, topaz at the Tarryalls, and quartz crystals and amazonite specimens at Pikes Peak.


Federal Public Lands
BLM-Managed Federal Public Lands
In Colorado, the BLM manages millions of acres of federal public lands.  Subject to federal restrictions, recreational rockhounds are permitted to collect rocks and gemstones from most federal lands. Some lands are withdrawn or reserved for certain purposes such as outstanding natural areas, research natural areas, recreation sites, national historic sites, etc.

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Mom and me looking for rocks in a Western Colorado stream in 2004


Specimen - Mt Antero

Mt. Antero, Colorado

Aquamarine & Other Specimens
Mt. Antero, Colorado
Mt Antero is one of the highest recreational rockhounding sites in the world.  At about 14,000 feet above sea level, the site has a short season.  Recreational rockhounders head here to look for aquamarine crystals as well as  smoky quartz, apatite, topaz, microcline, beryl, and other specimens.  The specimens occur in small cavities and pegmatites in granite.  

Specimen - amazonite and smoky quartz

Amazonite & Smoky Quartz

Amazonite & Smoky Quartz
Pikes Peak Region, Colorado
The Pikes Peak region is famous for its well-known and remarkably well-crystalized amazonite (a variety of microcline feldspar that is usually green or blue) and smoky quartz specimens that occur in  granite.  Amazonite occurs in granite pegmatites.  Crystal Peak in Teller County, Colorado also is a well-known site for high quality amazonite specimens.

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