Lone Mountain turquoise is the trade name for material recovered from the Lone Mountain mine in Esmeralda County, Nevada, one of the small group of historically important American turquoise sources whose goods have been continuously collected and traded since the deposit's commercial development in the early twentieth century. The mine has operated under various owners over its history and has produced a body of material that is recognised in the American turquoise market as one of the four or five top-tier high-grade origins.

Geological setting

The Lone Mountain deposit is hosted in the volcanic and altered sedimentary rocks of the Tonopah-Goldfield mineral belt of west-central Nevada, the same broad mineralised province that has produced gold, silver and turquoise from a number of mines over the past 150 years. Turquoise occurs as veins, nodules and seam fillings in the altered country rock, formed by the weathering and oxidation of copper-bearing primary minerals in the presence of phosphate-bearing groundwater.

Visual character

Lone Mountain turquoise is best known for two visual character types. The first is a clear, even-coloured medium to deep blue with little or no matrix, sometimes described in the trade as clear-skinned or non-spider-web; the colour is stable, with little tendency to drift toward green over time. The second is a strongly spider-webbed material in which the host blue is dissected by a fine network of dark brown to black matrix, sometimes red, in lines that resemble a spider's web. The spider-web variety is among the most collectable American turquoise material, with the very best examples reaching the top tier of price within the American turquoise market.

Trade authentication

The American turquoise market includes a substantial volume of misattributed material - stones from other mines marketed under more famous mine names, treated material marketed as natural, and reconstituted material marketed as solid. For Lone Mountain specifically, the most common misattributions are of look-alike spider-web material from Chinese sources or from less prestigious American mines. Trade authentication relies on the dealer's relationship with the mine and on the increasingly common use of laboratory testing for treatment, coupled with material-record documentation linking the parcel of goods to a specific mining and cutting batch.

Treatment

The American turquoise market handles substantial volumes of treated material, with stabilisation by impregnation with epoxy or related resins being the most common treatment. Lone Mountain top-grade material is generally hard enough in its natural state to take a polish without stabilisation, and the highest-grade Lone Mountain goods are sold as natural untreated. Sellers should disclose treatment status, and buyers expecting natural material from this mine should request explicit disclosure and, where the value justifies it, laboratory verification.

Market position

For the American Indian jewellery market, Lone Mountain occupies the top tier alongside Lander Blue, Number Eight, Bisbee and a small number of other named mines. Pieces incorporating documented Lone Mountain stones, particularly the spider-web grade, command meaningful premiums over comparable Native American silver and turquoise jewellery using less prestigious turquoise. The mine is no longer in active production at the levels of its peak years, which has supported the upward price trend for collected goods.