Topaz Mountain Gem Mine (Matucat Road deposits), Park County, Colorado, USAi

Regional Level Types
Topaz Mountain Gem Mine (Matucat Road deposits)	Mine
Park County	County
Colorado	State
USA	Country

Topaz Mountain Gem Mine

by Bob Carnein

Located at 39 degrees 6.345 minutes N, 105 degrees 23.591 minutes W, the Topaz Mountain Gem mine can be reached from Lake George, Park County, Colorado by following Park County Road 77 north for about 7 miles from where it intersects US Route 24; then turning right (northeast) onto Forest Service Road 211 (Matakat, aka Matukat, Matucat, Road) and driving approximately 2.5 miles to the entrance gate (on the north side of Matakat Road, just past the cattle guard). The locality occupies 2 Forest Service placer claims owned by Glacier Peak Mining, LLC, which is operated by Joseph L. Dorris and his family. COLLECTING IS STRICTLY PROHIBITED except when Mr. Dorris is present, and requires purchase of a bag of gem gravel. For detailed directions, conditions, and dates, go to http://pinnacle5minerals.com/GlacierPeakWeb/Visits/TopazVisits.htm.

The Topaz Mountain Gem mine is located in the Tarryall Mountains, a rugged, forested area that includes parts of Pike National Forest and the Lost Creek Wilderness. Starting in about 1990, Walt Rubeck, of Colorado Springs, located and developed 2 placer mining claims and set up a small, seasonal business that included a museum and store. Visitors could purchase buckets of topaz gravel that they could then screen on-site. Walt Rubeck died in the spring of 2005, at which time Joe Dorris took over the property.

Topaz occurs in the Tarryall Mountains in miarolitic cavities in pegmatites, in colluvial deposits, and in colluvial/alluvial deposits produced by glacial meltwater (Michalski, 1986). At the Topaz Mountain Gem mine, topaz occurs in 2 types of deposits. First, it forms well rounded "cutters" in small seams of deeper gravel that was deposited between large boulders. Second, it occurs in "pristine", sharply terminated crystals in poorly sorted granite colluvium. Both types probably originated in the rugged outcrops of 970- to 990-million-year-old potassium-rich granite that occur to the east and northwest of the mine. These outcrops are a part of the Redskin stock, a late intrusive phase of the Pikes Peak batholith. Topaz occurrences are concentrated along the contact between the Pikes Peak Granite and the Redskin stock.

Topaz crystals to over 6 cm and over 800 carats have been found at the locality. Typically, they exhibit lustrous, etched "chisel point" terminations that are coated by muscovite flakes or are pitted where muscovite flakes once occurred. More than 50 percent are colorless; 20 percent are pale "ice blue", and 20 percent are pinkish orange ("champagne" or "sherry"). Viewed down the c-axis, many exhibit a champagne colored "hourglass" shape. The blue color is stable, but the champagne color often fades in sunlight. Other colors are rare. Phenakite and schorl inclusions may be present; the writer has also observed unidentified inclusions of a dark green micaceous mineral and a black bladed mineral.

Other minerals at this locality include rare, euhedral zircon crystals (Joe Dorris, personal communication, 2012), common smoky quartz (some with phenakite or needly schorl crystals attached), milky quartz, microcline, albite, goethite, ferrocolumbite, and altered biotite.

Other Regions, Features and Areas containing this locality

References