338 SYSTEMATIC DESCRIPTION OF PRECIOUS STONES 



some others. They are prized by the American as a production of his native country, but 

 North America as a source of topaz has no commercial significance. 



Crystals of Kussiau topaz are remarkable both for size and beauty, stones of fine 

 quality and as much as 31 pounds in weight having been found. They are often cut at 

 Ekaterinburg, together with the variously coloured precious stones with which they are 

 found ; they find their way into the markets, in the rough or the cut condition, by way of 

 the fairs of Nizhniy Novgorod. 



As in Minas Novas, so also at most of the Russian localities, topaz and beryl occur 

 together ; the one mineral is never found without the other, except in the Altai Mountains 

 where beryl occurs, but no topaz has at present been found. The distribution of Russian 

 topaz is practically the same as that of Russian beryl, which has been already dealt with. 

 It will be unnecessary, therefore, to give here anything moi'e than a few facts relating 

 specially to the occurrence of topaz. 



Topaz is specially abundant in the neighbourhood of the village of Alabashka, near 

 Mursinka (Fig. 63a), in the Ekaterinburg district of the Urals. It is found in druses in 

 granite, together with smoky-quartz, beryl, large yellow crystals of felspar, small crystals of 

 white albite arranged in spherical groups, and red plates of lepidolite ; these miner'als all 

 occur in well-developed crystals, and the combination of different colours renders the druse 

 a very beautiful object. The smallest crystals of topaz are about the size of a pin's head, 

 while the largest are several centimetres in length. They are usually bluish in colour, as 

 represented in Plate XIII., Figs. 1 and la, sometimes light bluish-grey or greyish-white, 

 rarely colourless. As a rule, they occur singly in the druses, but sometimes grouped together 

 in parallel position. The usual crystalline form is the simple one repr'esented in Fig. 66c, 

 and in the coloured figure just cited. With regard to transparency, some ci'ystals are 

 perfectly clear, while others are only translucent ; the transparent ones are cut at the works 

 in Ekaterinburg and fetch a moderately high price. The gem-mines near Mursinka will be 

 again considered when we come to treat of amethyst. 



Another Uralian locality for topaz is the neighbourhood of the smelting works of 

 Miask, on the east side of Lake Ilmen. Its mode of occurrence here is the same, namely, in 

 drusy cavities in pegmatite ; these cavities are sometimes filled with a white clay, embedded 

 in which are topaz crystals which have been detached from the walls of the cavity. The 

 pegmatite-veins are here found at four places, traversing a rock known as miascite. 

 Associated with the topaz is green felspar (amazon-stone), in which it is frequently embedded, 

 also phenakite, mica, and other minerals. Two varieties of topaz occur here. One is 

 colourless and perfectly transparent, like the " pingos d'agoa " of Brazil, and occurs as 

 symmetrically developed crystals rich in faces. The other variety is of a dirty yellowish- 

 white colour, translucent only at the edges, and so fissured and decomposed or, as it is 

 described at the place, rotten, that the crystals, which are bounded by only few faces, may 

 be easily crushed between the fingers. Both these varieties occur in crystals of about the 

 same size as those found at Alabashka. 



Topaz is also found in the gold-washings, belonging to a merchant named Bakakin, in the 

 valley of the Sanarka (a tributary of the Ui, which itself feeds the Tobol), as well as in a few 

 tributary streams in the Southern Urals (Government Orenburg). The crystals found here 

 are so very similar to Bjuzilian topaz that their Uralian origin was at first doubted. They 

 Tisually retain their crystalline form, which is simple, like that shown in Fig. 66a. Their 

 colour is generally some shade of yellow ; some, however, are red and a few quite colourless. 

 Many are beautifully transparent. The largest crystals have a length of 2^, and a thickness 

 of f centimetres. The topaz in these river-sands is associated with a great variety of 



