THE TOPAZ LOCALITY 179 



located about 40 miles north of Sevier lake and a little more than that 

 distance northwest of the town of Deseret. The name Thomas range is 

 not, however, familiar to residents of Deseret and vicinity, who refer to 

 it as the Dugway range and who speak of the topaz locality proper as 

 Topaz moimtain. As will appear later, the crystals of topaz are not lim- 

 ited to a definite portion of the range, but are found scattered throughout 

 a rhyolite formation that extends many miles to the north and west ; but 

 as the crystals are extraordinarily abundant at this particular place, it 

 will be convenient to refer to the locality as "Topaz mountain." 



On the most direct road from Deseret to Topaz mountain one passes 

 through a small range locally known as the Drum mountains, which are 

 composed — as far as visible from the road — of blue limestone and quartz- 

 ite, with flows of basalt and rhyolite and probably also of andesite. Sev- 

 eral small mines -and prospects with copper and gold ores have been 

 worked here in the past and were under active investigation at the time 

 the writer visited the region. 



In these so-called Drum mountains, and close to the above mentioned 

 mines, is located the postoffice called Joy, in Juab county. Eigh^ miles 

 northwest of Joy, and also in Juab county, is the Topaz mountain. 



Description of Topaz Mountain 



On the east side the range, of which Topaz mountain is a part, stands 

 up very conspicuously, like a sharp ridge, and may be seen for many 

 miles. Its color is a very light gray or almost white compared with the 

 dark brown to reddish colored hills that are seen to skirt the ridge on the 

 north and south and that run out some 3 miles to the eastward and form 

 foothills to the main mountain mass. As a matter of fact, however, 

 except for a spur some half mile in length that runs out southeasterly 

 from the main crest and nearly at right angles thereto, the mountain 

 mass does not form a ridge, but is rather a greatly dissected tableland 

 that rises very precipitously on the southeastern face for a distance of 

 some 4 or 5 miles to an estimated height of 1,000 or perhaps 1,200 feet 

 above the base, hut that to the westward and northwestward stretches out 

 apparently indefinitely. 



The rocks that form this part of the Thomas range are volcanic in 

 origin and lie upon a level or more or less rolling platform of sedimenta- 

 ries of age unknoAvn to the writer, but quite possibly Carboniferous. The 

 only sedimentary rock actually seen, except some of volcanic origin, was 

 a bluish gray limestone that lies horizontal in the nearly level stretches 

 southeast of the range. On this limestone lies a buff-colored rhyolitic 



