498 SYSTEMATIC DESCRIPTION OF PRECIOUS STONES 



one time much more highly esteemed than it is now ; a fine stone of a bright green colour 

 and considerable translucency was once worth upwards of £5, while now it would fetch 

 scarcely half that sum, and stones of inferior quality are of course worth still less. 

 Chrysoprase, however, is the most valuable of those compact varieties of quartz which are 

 used as gems, and generally speaking is one of the most highly esteemed of the so-called 

 semi-precious stones. 



This beautiful mineral is used also as a decorative and ornamental material for 

 furniture, mosaics, &c. For example, two tables inlaid with chrysoprase were ordered by 

 Frederick the Great for the Sans Souci palace at Potsdam, and the same substance figures 

 in the beautiful mosaic of the walls of the fourteenth-century Wenzel Chapel in the 

 Hradschin at Prague. 



Chrysoprase occurs in thin plates and veins, sometimes of considerable size, which are 

 usually embedded in serpentine, of which it is a weathered product, and from which it 

 derives its nickelous colouring constituent. Large pieces are seldom uniformly coloured ; 

 portions of darker and finer colour iiierge gradually into others which are pale or almost 

 white, or into the yellow or brown common hornstone, which must be removed before the 

 better portions are cut. Masses are frequently met with in which the hornstone passes 

 in places into other varieties of compact quartz, such as chalcedony, and into opal. The 

 latter mineral has been formed at the same time and in the same manner as chrysoprase, 

 and is sometimes coloured green like the prase-opal already mentioned. 



The most important localities for chrysoprase are in Silesia, where it occurs at various 

 places in the neighbourhood of Frankenstein, to the south of Breslau. At Kosemiitz 

 chrysoprase of a deep, and sometimes also of a pale, colour occurs with chalcedony, opal, 

 asbestos, and other minerals in veins in serpentine. Similar occurrences exist at Baumgarten 

 and Grochau, while at Glasendorf, Protzan, and Schrebsdorf the mineral lies in a yellowish- 

 brown clayey earth, which overlies the serpentine aud is a product of its decomposition. 

 The chrysoprase frequently occurs so close to the surface that it is washed out by heavy 

 rains and collected by peasants. Specimens of moderately large size can be obtained at 

 Frankenstein, but they contain a good deal of impure and light-coloured material. The 

 stones of a bright green colour are usually rare ; the finest come from Glasendorf. 



According to an early account (1805) there exists in this district a vein of chrysoprase, 

 three (German) miles in length, traversing the serpentine and associated rocks. This was 

 accidentally discovered in 174-0 by a Prussian officer at the northern end of the vein by the 

 windmill of Kosemutz. Frederick the Great interested himself in this Silesian stone, and 

 utilised it in the decoration of the Sans Souci palace. The occurrence was probably only 

 rediscovered by the Prussian officer, for the chrysoprase in the Wenzel Chapel at Prague 

 no doubt came from Silesia, and therefore must have been known in the fourteenth 

 century. At the time of the rediscovery of this fine green stone the name chrysoprase was 

 bestowed on it, although the name had been given by the ancients to an entirely different 

 mineral. 



There are no other European localities of any importance. Dark apple-green stones 

 come from Wintergasse, in the Stubachthal, in Salzburg ; and Ruda, in Transylvania, is 

 perhaps another locality, but at both the mineral occurs only sparino-U-. 



A certain amount of chrysoprase also occurs at a few places outside Europe. Very 

 fine stones come from India, but exactly where they are found does not seem to be known. 

 The mineral is also found in the nick el- ochre mine at Revdinsk, east of Ekaterinburg in the 

 Urals, and at various places in North America. The most important of the latter is the 

 nickel mine on Nickel Mount, near Riddle, in Douglas County, Oregon, where the mineral 



