May 8, 2003
Gemstones Identified in Wyoming

Research by the Metals and Precious Stones Section at the Wyoming State Geological Survey (WSGS) has now identified several different gemstones in Wyoming. Not only does Wyoming have 23 known diamond deposits, it also has a number of colored gemstones including sapphire, iolite, peridot, pyrope garnet, and chromian diopside.

One of the more interesting deposits, Palmer Canyon west of Wheatland, was discovered by the WSGS in 1995. This deposit contains corundum gemstones, some of which have been cut, producing some attractive pink to red sapphires. The deposit also contains transparent, blue cordierite (known as iolite by the gemologist), which is a popular sapphire-blue gemstone. Specimens of gem-quality iolite, weighing more than 3000 carats (approximately fist size), were found by W. Dan Hausel of the WSGS during field investigations. Based on similarities in geology, the WSGS also believes that similar deposits may possibly be discovered at several other localities in Wyoming.

Another colored gemstone found in the state is peridot, which is gem-quality olivine. Olivine was first reported in the Leucite Hills northeast of Rock Springs about 4 decades ago during geological research by the University of California at Berkley. However, no one paid attention to the quality of the olivine until the WSGS examined it. The material was transparent, light-green with potential to produce the gemstone peridot. Some peridot was recently cut from the olivine and yielded very attractive gemstones.

Other gemstones described by the WSGS include purple to yellow-orange pyrope garnet and emerald-green chromian diopside. These yield gemstones with very attractive colors. They are found at a number of localities in southern Wyoming, sometimes even found with diamonds. Some of these minerals were recently faceted and images of them can be viewed on the WSGS website at

Press Release
from the Office of the Wyoming State Geologist
Ron Surdam, State Geologist