Number 8 turquoise comes from the Number 8 mine near Carlin in Eureka County, Nevada, one of the iconic North American turquoise sources of the twentieth century. The mine is celebrated for material in intense sky-blue to robin's-egg blue colour with distinctive black or dark-brown spider-web matrix patterns. Active principally from the 1920s through the 1970s, the deposit is now largely depleted, and authenticated Number 8 turquoise commands premium prices in the contemporary collector and Native American jewellery markets.

The mine and its history

The Number 8 mine was discovered in 1925 and operated commercially through the mid-twentieth century. Production peaked in the 1950s and 1960s, with the mine yielding turquoise in a remarkable range of qualities, from the famous bright-blue spider-web material to greener, less matrixed stones used in commercial jewellery. The deposit is hosted in a fault zone associated with the Carlin trend — better known for its gold deposits — and the turquoise occurs in altered volcanic and sedimentary rocks.

By the late 1970s, mining had effectively ceased as the accessible deposits were exhausted. Some material has been recovered from old dumps and tailings since, and very limited production from peripheral pockets has occurred, but the mine is not in active commercial operation. The contemporary supply of Number 8 turquoise is therefore principally from existing inventories — pieces in the hands of dealers, jewellers, and collectors — rather than from continuing production.

Material characteristics

The most desirable Number 8 material shows an intense sky-blue to robin's-egg blue body colour, often with a slight greenish modifier. The matrix — the dark veining that runs through the stone — varies from fine spider-web patterns to bolder black or dark-brown lines, with the finest spider-web material commanding the highest premiums. The matrix in Number 8 turquoise is characteristically quartz-rich, lending it a hard, sharp-edged appearance that persists through cabbing and polishing.

Hardness varies across the deposit, with some material approaching the high end of the turquoise hardness range (5 to 6 on the Mohs scale) and other pieces softer and more porous. As with most natural turquoise, treatment is common — wax stabilisation, polymer impregnation, and dyeing have all been applied historically. Untreated Number 8 turquoise of fine colour and matrix is rare and commands corresponding premiums.

Use in Native American and contemporary jewellery

Number 8 turquoise has been used extensively in Native American jewellery, particularly in Navajo, Zuni, and Hopi work. Heavy silver settings, hand-fabricated bezels, and the distinctive Southwestern aesthetic combine with the rich blue-and-black contrast of the stone to produce some of the most recognisable American jewellery of the twentieth century. Notable Native American silversmiths and contemporary makers continue to use Number 8 material, drawing on existing supplies of authenticated rough.

Outside Native American work, Number 8 turquoise appears in studio jewellery, bespoke commissions, and high-end Western-style designs. The premium for genuine Number 8 material over generic American or Chinese turquoise reflects both the scarcity of supply and the strong collector and aficionado market.

Authentication

Authenticated Number 8 turquoise typically comes with documented provenance — chain of custody from a known dealer or estate, period photographs, or accompanying paperwork. Visual identification is possible for experienced eyes but not reliable in isolation, since other Nevada deposits produce visually similar material. Buyers paying significant premiums for Number 8 attribution should insist on provenance documentation or laboratory examination, particularly given the active market in misidentified and falsely attributed turquoise.

Care and wear

Turquoise generally requires careful handling. The stone is sensitive to heat, chemicals, body oils, and prolonged moisture, all of which can shift colour or cause matrix darkening. Stabilised material is more resilient than untreated stone but still benefits from gentle care. Cleaning should be by soft cloth and minimal moisture; ultrasonic and steam cleaning are not recommended.

Further reading

• GIA Gems & Gemology — turquoise reference
• International Gem Society — American turquoise sources
• Mindat — Number 8 mine specimen and locality data