Colorado is an extraordinary state for rockhounding. It’s famous for its silver and gold mines, but there’s a remarkable variety of minerals, gemstones, fossils and other geologic treasures to be uncovered. The first amateur geologists in the area were prospectors looking for gold and other minerals of commercial value. More recently, people have been drawn to amateur geology for recreational purposes, mainly for the beauty rocks and minerals provide. After all, it’s easy to be transformed into a rockhound. Simply noticing a shiny stone or glimmering crystal while on a hike and picking it up can start the “fever.”
The Front Range offers an abundance of minerals, gemstones, crystals and fossils to anyone willing to look for them. For the casual collector or the obsessed amateur, there’s a little something for everyone, just about everywhere. It’s a matter of paying attention. Good places for a collector to look are quarries, road cuts, rocky hills and mountains, and streams.
Once rocks, gems and minerals begin to catch your eye, suddenly every dirty rock you used to walk past becomes much more interesting. These discoveries can delight the modern-day amateur prospector, just as they did in the mid-1800s for the miners who began the mining rushes.
The processes that formed the Rocky Mountains, including violent tectonic forces, volcanic and glacial activity and erosion, have exposed rocks and minerals formed more than 55 million years ago, well before the mountains were raised. While many rocks and minerals commonly found in the area are considered beautiful, and even valuable, they all tell a story about the region’s geologic past.
The Front Range mountains feature “up-thrusts” exposing ore deposits and revealing marine deposits with evidence of past ocean life. Mines producing large amounts of gold, silver, tungsten and molybdenum have made the region famous, but there is also feldspar, mica, quartz, amethyst, pyrite, fluorite, black tourmaline, argentite and many more. Some are pretty, some are useful and some are simply intriguing.
To get started on your own rockhounding journey, find a website or guidebook specific to where you want to go or what you’re looking to find. Better yet, stop in a local rock shop to learn about the regional geology, find other hobbyists and groups, identify your finds or add to your collection the easy way. There are many dedicated rock shops in our Front Range mountain towns, but also keep an eye out for gem and mineral specimens in unexpected places from random gift shops to gas stations.
The only equipment needed, beyond the basics used for hiking and scrambling on rocks, is a geologist’s hammer. The small tool has a pick-like point on one end, and a flat hammer on the other. The hammer end is for breaking rocks, and the pick end is mainly used for prying and digging into crevices. Rock collectors may also bring a sledgehammer to break hard rocks and a shovel. A guide that describes sites, incudes good maps and identifies what you find can also be very useful.
Once you really get into it, learning to pan for gold can be helpful. It’s obviously good for finding that precious metal, but the weights of gemstones are heavy enough to make gold panning techniques useful. Classes are available in many mining communities. It’s also good to learn to recognize minerals and gems in their natural state. Also, if you join prospecting club, you can gain access to the club’s territorial claims and rock-hunting tips.
Be aware. Do your gem hunting in public areas or properties operated by the Bureau of Land Management. Working on private land is considered claim-jumping and is illegal. There are many different laws in place regarding the collection of rocks and minerals from public areas, so it is advisable to read up on local laws before prospecting. Rock and mineral collecting is prohibited in most if not all national parks in the United States. To avoid trespassing, the amateur rockhound or prospector should check with local BLM field offices for locations of existing mining claims.
Mineral specimens, precious and semiprecious gemstones, petrified wood, common invertebrate and plant fossils may be collected on public lands without charge or permit in reasonable amounts—what one person can fit in a 5-gallon container in one day—as long as the specimens are for personal use and not collected for sale or barter to commercial dealers. No undue or unnecessary degradation of the public lands is allowed during the removal of rocks, minerals, gemstones, or fossils. Other rules and restrictions may be in effect in a particular area, so do your homework if you’re unsure.
If you find yourself being pulled in by rockhounding, be sure to familiarize yourself with the code of ethics for rock, fossil and mineral collectors. When rockhounding: Always respect both private and public property, and do no collecting on privately owned land without the owner’s permission. Keep informed of all laws, rules, and regulations governing collecting on public lands, and observe them.
Also, use no firearms or blasting materials in collecting areas. Cause no willful damage to property of any kind. Leave all gates as found. Fill all excavation holes and do not contaminate wells, creeks, or other water supplies. Follow all fire restrictions and leave collecting areas free of litter.
In Clear Creek County, the Idaho Springs, Georgetown and Silver Plume areas have more than 600 former mines, from small prospects to major producers. Needless to say, the region is known for its minerals. There is argentite, chalcopyrite, galena, gold, pyrite, quartz, silver and sphalerite. The nearby Genesee Mountain Dike, an exposed pegmatite dike on the north side of U.S. 40, has been picked over for many years, although some grossular garnet pieces can still be found. Look for epidote, grossular, scheelite and titanite.
Hundreds of mines also dot the area around Central City and Black Hawk in Gilpin County. Amethyst, chalcopyrite, galena, gold, pyrite, quartz and silver can be found here. Nearby Golden Gate Canyon offers collection of garnet and tourmaline in roadcuts.
In the Tungsten Belt area, more than 100 tungsten mines stretch from Boulder to Nederland. The Peak to Peak Highway passes through the area which offers argentite, barite, ferberite, fluorite, galena, huebnerite, pyrite, scheelite and sphalerite. Above Nederland in the Caribou area, metal sulfides can be found in mine dumps as well as argentite, chalcopyrite, chlorargyrite, galena, gold, pyrite, quartz and silver.
Around 80 small mines were dug after mineralogists found gold tellurides in the Gold Hill area which also produced gold, silver, lead, zinc and tungsten. Look for chalcopyrite, galena, gold, petzite, pyrite, sphalerite and sylvanite.
The Jamestown area produced gold, by-product base metals and fluorspar. Collectors still find fluorescent fluorite in dumps as well as galena and pyrite in the area.
Crystal Mountain is located 20 miles west of Fort Collins and is composed of pegmatite material. Most of the crystals from this location are small, although some nice-sized topaz crystals have been found by collectors. This is Colorados best locality for apple-green chrysoberyl.
Check out the Rocky Mountain Conservancy offering a variety of classes and workshops to discover Rocky Mountain National Park’s geologic wonders. Among other opportunities, kids ages 4-6 can discover what puts the “rock” in Rocky Mountain National Park on the “Rocky Mountain Rock Hunt,” July 7. Everyone can learn to identify common rocks and minerals, and discover what they can tell us about the geologic past at “Rocks & Minerals: Exploring the Foundation of RMNP,” July 21. Become acquainted with the vastness of geologic time and the power of geologic processes through the study of rocks and physical features along one of the highest and most spectacular roads in North America at “Geology of Trail Ridge Road,” July 22.
Mountain Area Rock Shops & Rockhounding Resources
1514 Miner St., Idaho Springs
BLM Colorado State Office
2850 Youngfield St., Lakewood
Colorado Prospector Club
Flatirons Mineral Club – Boulder
Fort Collins Rockhound Club
Front Range Rockhound Sites
Gypsum Rose Minerals & Fossils
1800 Miner St., Idaho Springs
Little Gem & Mineral Club
121 Main St., Central City
5 E. First St., Nederland
Red Rose Rock Shop & Dick’s Rock Museum
490 Moraine Ave., Estes Park
Rocky Mountain Conservancy
Self-Guided Front Range Geologic Tour
The Ore Cart Rock Shop
119 W. Elkhorn Ave., Estes Park
Originally published in the July 2016 issue of the MMAC Monthly