Rockhounding in Colorado

Chaffee County

Mount Antero is the highest gem locality in the United States, with aquamarine and beryl occurring in granite cavities above timberline near its 14,269-foot summit. Aquamarine is Colorado's state gemstone, and the peak also yields phenakite, topaz, smoky quartz, and fluorite. The collecting ground lies in San Isabel National Forest, where the Forest Service permits casual hand-tool collecting for personal use on open land.

Aquamarine, Beryl, Phenakite, Smoky Quartz

Gunnison County

Italian Mountain holds one of the few genuine lapis lazuli localities in the United States, a contact-metamorphic deposit in marble that has produced some of the largest North American lapis specimens. Grossular garnet, diopside, pyrite, and calcite occur in the same skarn. The site sits on open Gunnison National Forest land outside designated wilderness.

Lapis Lazuli, Grossular Garnet, Diopside, Pyrite

Gunnison County

The Quartz Creek, or Brown Derby, district is Colorado's most fractionated lithium-cesium-tantalum pegmatite field, mapped by the USGS as more than 1,800 pegmatite bodies. They carry beryl, lepidolite, pink and green tourmaline, and rare columbite-tantalite. The dikes sit on Gunnison National Forest land where personal hobby collecting with hand tools is allowed.

Beryl, Tourmaline, Lepidolite, Albite

Larimer County

The Crystal Mountain pegmatite district, mapped in USGS Bulletin 1011, contains beryl in roughly a quarter of its pegmatites, including aquamarine, alongside muscovite, fluorapatite, and bismutite. The district sits on Roosevelt National Forest along upper Buckhorn Creek west of Fort Collins. Garnet and schorl tourmaline occur in the zoned pegmatites.

Beryl, Aquamarine, Fluorapatite, Muscovite

Mineral County

Wolf Creek Pass cuts through Conejos Formation basalts whose gas cavities are lined with zeolites, including mordenite reported among the finest in North America, alongside amethyst-bearing geodes. Heulandite, chabazite, and calcite occur in the same amygdules. The collecting exposures along US 160 sit on San Juan and Rio Grande National Forest land outside designated wilderness.

Amethyst, Mordenite, Heulandite, Chabazite

Douglas County

Devils Head sits in the Pikes Peak granite of the Rampart Range, where weathered pegmatite pockets have produced large topaz and smoky quartz crystals along with amazonite and fluorite. The locality lies on Pike National Forest land, and personal-use specimen collecting with hand tools is allowed on open ground. It is one of the classic crystal-pocket areas of the Front Range.

Smoky Quartz, Topaz, Amazonite, Fluorite

El Paso County

St. Peters Dome is a Pikes Peak granite peak in Pike National Forest where the historic Cheyenne fluorspar district left dumps that still yield loose purple, green, and white fluorite within a short walk of the parking area. Smoky quartz, amazonite, zircon, and topaz occur in the same granite. The collecting ground sits south of the Bear Creek watershed closure, so it remains open to casual hand-tool collecting.

Fluorite, Smoky Quartz, Amazonite, Zircon

Park County

The Tarryall Mountains are one of the better topaz localities in the Pikes Peak region, with smoky quartz and pale amazonite in pegmatites of the Redskin Stock. Trails from Spruce Grove Campground on Pike National Forest lead to mine tailings where collectors have found smoky topaz. Personal-use collecting with hand tools is allowed on the surrounding open Forest Service ground.

Smoky Quartz, Topaz, Amazonite

Saguache County

The thunderegg beds northwest of Del Norte have yielded plume and moss agate from rhyolite flows since the late 1800s, with chalcedony, common opal, and quartz-lined cavities documented at the locality. The beds lie on Rio Grande National Forest and adjacent BLM land at the south end of the La Garita Mountains. Plume agate is the signature material.

Plume Agate, Moss Agate, Chalcedony, Common Opal

Saguache County

Crystal Hill near La Garita is documented by the USGS as a source of clear rock crystal and pale lavender amethyst in brecciated volcanic rock, a San Luis Valley collecting site worked since the 1880s. The BLM reclaimed the old mine workings around 2009 and allows public collecting on the reclaimed ground. Smoky quartz and manganese oxides occur in the same host.

Amethyst, Quartz, Smoky Quartz