Bureau of Land Management, Utah.
Topaz, Utah's state gem, is a semi-precious gemstone that occurs as very hard, transparent crystals in a variety of colors. The topaz crystals at Topaz Mountain are naturally amber colored but become colorless after extensive exposure to sunlight. The crystals formed within cavities of the Topaz Mountain rhyolite, a volcanic rock which erupted approximately six to seven million years ago from volcanic vents along faults in the area. Topaz Mountain is one of the world's great places to find topaz. If you search the washes and slopes on the south side of the mountain you will find small topaz crystals glimmering in the sunlight. If you search seams in the rhyolite, you may find gem-quality crystals. Topaz Mountain is located in a remote area where there is no water and no services are provided. You should always carry food, plenty of water, tools and emergency equipment. To dig the topaz, helpful tools include a rock hammer or regular hammer, screw driver, bags for your gems, hiking boots, hat, sun screen, bug repellant and once again don t forget the water! Jeans are a wise choice since while you are digging you are often on your knees on the rough and jagged rocks.
From Nephi, travel southwest from Nephi on Hwy 132 for about 34 miles to the town of Lynndyl and the junction with Hwy 6. Continue south on U.S. Highway 6 for about 5 miles and then turn west onto Highway 174 (Brush Wellman Road). This intersection is well marked. Drive northwest on the paved Brush Wellman Road for about 37 miles, to the signed dirt road lead?ing up to Topaz Mountain. The mountain will be clearly visible at this point. The most popular rockhounding spots are along the mountain?s southern slope.