GEOCHEMICAL ANALYSIS OF CENOZOIC TOPAZ RHYOLITE BEARING RED BERYL FROM THE THOMAS RANGE AND WAH WAH MOUNTAINS IN WESTERN UTAH

The Thomas Range, Juab County, Utah and the Wah Wah Mountains, Beaver County, Utah are amongst the few places worldwide that contain red beryl. The Wah Wah Mountains hosts the Ruby-Violet claim, which is the only known reservoir of gem quality red beryl. The rhyolite samples collected from the Thomas Range date to 6-7 Ma. The rhyolites in the Wah Wah Mountains are 22-18 Ma. Extensive research has been done on red beryl; the purpose of the geochemical research that has been done compares one or two samples from each location. The Thomas Range mineral assemblage, quality of mineral, and size of minerals changes from location to location. This research looks at a variety of samples from the Thomas Range and Wah Wah Mountains, including samples that contain red beryl. The Wah Wah Mountains and Thomas Range samples are compared to Garnet Hill, Nevada rhyolite, a vapor phase non-topaz rhyolite.

Another point of comparison is made with the Danburg granite. Danburg granite is an Alleghenian biotite granite with rapakivi texture. This comparison is made because of the possible relationship between rapakivi granite and the topaz rhyolites. Rapakivi granites and topaz rhyolites share a similar mineralogy and similar geochemical signatures (Christiansen, Haapala and Gart, 2007).

In June 2015, students from the University of West Georgia visited the Thomas Range and Wah Wah Mountains of Western Utah to collect samples for research. Samples were collected from the south eastern part of the Wah Wah Mountains and from the following areas in the Thomas Range: Topaz Mountain, N 39°46.438’ W 113°05.350,’ eastern side of the Thomas Range, and Topaz Valley. The rhyolite samples collected from the Thomas Range tend to be white, vesicular, with sporadic recurrent flow banding, and has some iron staining. Both rhyolites tended to be porphyritic aphanitic. At Topaz Mountain some fractures in the rhyolite were filled in with kaolinite. Phenocrysts of topaz, red beryl, bixbyite, and hematite occur in the vugs of the kaolin. The rhyolite from the Wah Wah Mountains ranges in color from red to white, contains some flow banding and clay-filled fractures, is vesicular, with phenocrysts of quartz, sanidine, and topaz. The Garnet Hill rhyolite contains phenocrysts of tridymite, garnet, and sanidine.