Thursday, July 16, 2009

Topaz, Thomas Range, Topaz Mountain, Utah

Utah Topaz

Although the Thomas Range, Utah contains red beryl, bixbyite, and wonderstone, it is most famous for topaz. Beautiful topaz mineral specimens come from this location.

The Thomas Range erupted as rhyolite 32 to 33 million years ago. The topaz formed from steam moving through lithofacies (bubbles and cracks) within the rhyolite long after the rhyolite had cooled. The largest crystal reported from the Thomas Range came from the Maynard Bixby claim and was a whopping five inches long and over two inches wide. However, most topaz crystals from the Thomas Range are less than 1 inch.

Generally, topaz doesn’t form in the same cavities or vugs as beryl even though they are often with in close proximity to each other. In the Thomas Range, it is not uncommon to find topaz and red beryl attached to each other, making this deposit even more remarkable. These small specimens are highly sought by mineral collectors.

Utah topaz has another famous distinction: It fades when exposed to UV light. This explains why all the crystals on the ground (that are found in abundance) are clear. Once exposed to sunlight, they are rapidly bleached of their color. The color can be restored through irradiation. Because the color fades in light, Utah topaz is only rarely made into jewelry.

Faceted stones are sought by collectors. Quality bulk pieces can be tumbled if they lack any matrix.

Topaz is one of the most popular gemstones in the world because of its color, luster, hardness, and abundance. Topaz is Utah's State Gemstone.

Utah is famous for the light brown topaz crystals from the Thomas Range and more specifically from Topaz Mountain at the southern-most tip of the range. With some work, just about anyone can find a great treasure here. It takes is patience, patience, and more patience, plus good hammers and chisels, and stamina.

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