TOPAZ: OCCURRENCE IN THE UNITED STATES 337 



of 2 or 4 inches, have been described by L. von Eschwege. Such large stones, however, 

 are almost always more or less faulty, and are rarely suitable for cutting. The majority 

 are much smaller, about the length and thickness of a little finger. The form of the 

 crystals is usually quite simple, like that shown in Fig. 66a. 



In this locality excavations are made in the clayey mass in which the topaz occurs, 

 and the larger nests, when met with, are carefully removed and opened. The crystals 

 which lie loose in the clay are obtained by allowing a stream of water to play upon 

 the loosened masses of clay in the mine. By this means the lighter material is washed 

 away, and the heavier topaz crystals caught in the meshes of a net spread out for that 

 purpose. 



The annual output of topaz at one time amounted to as much as 18 hundredweight, 

 but on an average was not more than 7 or 8 hundredweight, a large proportion 

 beipg yielded by the estates of Capao de Lana and Boa Vista, which are specially rich 

 in topaz. It is said that the mining of topaz at one time afforded employment to as 

 many as fifty persons. The stones find their way into the market by way of Rio Janeiro, 

 some being cut on the spot. The valley of Ouro Preto is studded with innumerable 

 abandoned mines, mute witnesses of former activity in this district. As the demand for 

 these stones gradually fell off^ the mines were one by one abandoned, and systematic work 

 has now ceased for a long time. Many are of opinion that the locality is practically 

 exhausted ; others aver, however, that there are still rich treasures to be found. 



The occurrence of topaz in Mexico is of little commercial importance. It is found at 

 La Paz in the State of Guanaxuato, at San Luis Potosi, and at Durango, in stanniferous 

 deposits. The crystals are pale in colour or colourless and water-clear. 



The mineral is widely distributed in the United States of North America, but 

 crystals of gem-quality are somewhat rare, the best material coming from the Western 

 States. Transparent and water-clear, bluish, and greenish crystals are found, together with 

 beryl and other minerals, in granite, at Harndon Hill, near Stoneham, in Maine ; also at 

 other places in the neighbourhood, and at North Chatham in New Hampshire. Topaz 

 crystals, very similar to those from Saxony, are found in the granite of Trumbull, 

 Connecticut, but they are usually cloudy and rarely of gem-quality. 



In Colorado fine crystals of a pale blue colour, or colourless and water-clear, and 

 occasionally of considerable size, are met with. They occur with phenakite and other 

 minerals in drusy cavities in granite at various points in the Pike's Peak region, in El Paso 

 County. Thus, for example, at Florissant, twelve miles north of Pike's Peak, they are 

 found embedded in green felspar (amazon-stone) ; and in the neighbourhood of Devil's 

 Head Mountain, about thirty miles from Pike's Peak, colourless, reddish, wine-yellow, and 

 pale blue crystals, similar to those of Mursinka in the Urals, are found in the solid rock or 

 loose on the ground. Another, not altogether unimportant, locality is Mount Antero, 

 about ten miles north of Salida, in Chaffee County, Colorado. The Colorado localities 

 have yielded the best specimens of North American topaz of gem-quality ; two of the 

 largest after cutting weighed respectively 125 and 193 carats. At several places topaz has 

 been found also in younger volcanic rocks, namely, in rhyolites ; for example, at Nathrop in 

 Chaffee County, and on Chalk Mountain in Colorado. 



Very fine colourless crystals are met with embedded in solid rock, or loose in its 

 weathered product in the Thomas Range, forty miles north of Sevier Lake in Utah, and at 

 the same distance north-west of the town of Deseret on the Sevier river. The topaz found 

 at these localities in the State of Utah is perhaps the finest in the United States. 



A few stones of gem-quality have been met with at all the localities mentioned, and at 



