Thomas Range

Mindat.org

Juab County, Utah, USA

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Key Information

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  • The Thomas Range in Juab County, Utah, is a renowned mineral locality, especially for topaz, attracting crystal enthusiasts.

  • It is located in western central Utah, near Delta, within the Great Basin region, with nearby landmarks like Topaz Mountain and Spor Mountain.

  • Research suggests it features a variety of minerals, including uncommon ones like bixbyite and holfertite, formed in volcanic rhyolite and tuff.

  • The evidence leans toward a mining history starting in the 19th century, with public collection currently allowed, but commercial efforts were largely unsuccessful.

  • It seems likely that the area has a cold semi-arid climate, influencing its desert ecology, with cultural ties to nearby Delta, including its WWII internment camp history.

Geographic Location

The Thomas Range is situated in Juab County, western central Utah, USA, near the city of Delta. It trends north to south and is part of the Great Basin, known for its unique desert landscape. Nearby, you'll find Topaz Mountain to the south and Spor Mountain to the southwest, making it a notable spot for mineral explorers.

Minerals Produced

This range is famous for topaz, Utah's state gem, available in colors from imperial sherry to clear. Beyond topaz, it hosts a diverse array, including fluorite, bixbyite, pseudobrookite, holfertite, red beryl, opal, and bertrandite. The presence of uncommon minerals like holfertite, a uranium mineral, adds an unexpected layer of interest for collectors seeking rare finds.

Geological and Mining History

Geologically, the Thomas Range consists of Miocene-aged rhyolite domes and stratified tuff, formed by explosive volcanic activity. This volcanic history has created cavities where minerals like topaz formed, offering a glimpse into Earth's fiery past. Mining history dates back to the 19th century, with early explorations by figures like Captain Simpson and Maynard Bixby, who discovered new minerals. While commercial mining for fluorspar and beryllium was attempted, it was largely unsuccessful, and today, the area is open for public collection with hand tools, preserving its allure for enthusiasts.

Local Culture and Climate

Culturally, the Thomas Range is tied to mineral collecting, drawing enthusiasts globally. Nearby Delta, with a population of about 3,622, has historical significance, including being the site of a Japanese internment camp during World War II, adding a human dimension to the area. The climate is cold semi-arid (BSk), with low rainfall and significant temperature swings, shaping a desert ecology with species adapted to dry conditions, which may influence mineral preservation.

Citations

Wikipedia