What Is Utah's State Gemstone?

By Olivia Barney

Have you ever wondered what precious and pretty gems can be found in Utah? Our diverse landscape is full of geologic wonders that make it a treasure trove for geologists, mineralogists, and paleontologists alike! Utah even has an official state gemstone: topaz. Learn about topaz from Dave Richerson, a mineralogy specialist here at NHMU, then keep reading for more information!

Utah’s State Gemstone 

Topaz has been Utah’s official state gemstone since 1969. It earned the title thanks to the abundance of topaz found in the Thomas Range, a group of mountains that extend north-south in Juab County, Utah.

Topaz can come in a variety of colors, but in the Thomas Range, it’s typically a warm, amber color. With prolonged exposure to the sun, however, it will lose its hue and become completely colorless! But that isn't the only variety you can find here in Utah. At a couple sites, the topaz crystals are a bright pink that does not change color. At the Solar Wind Mine, the topaz starts out amber color but changes to pale pink when bleached by the sun. At several sites, the topaz crystals are filled with inclusions of hematite, which make the crystals appear black.

How Does Topaz Form?

Cognac-colored topaz found at Topaz Mountain, Thomas Range, Juab County, Utah, USA

Volcanic flows produce lots of air bubbles, and once the magma cools, those bubbles are preserved in the rock. These open spaces make the perfect home for gems and minerals — Topaz, for example, can be found in a volcanic rock called rhyolite.

What is Topaz Mountain?

Topaz Mountain is part of the Thomas Range, and it’s a favorite rockhounding location for local Utahns and tourists alike! It’s one of the world’s greatest locations to find topaz, as the area features a plethora of rhyolite rocks that topaz formed in. This rhyolite formed from a series of volcanic eruptions that occurred 6-7 million years ago. The topaz crystals grew in the small open spaces such as gas bubbles during the eruption and while the magma was cooling. Thus, these beautiful topaz crystals are older than six million years!