MINERALS IN ART AND ARCHEOLOGY — GETTENS 555 



thick are on exliibition in the Freer Gallery of Art (pi. 2, fig. 2). 

 A number of good examples of "tomb jade" are pictured, many in 

 color, in a recently published work on "Chinese Art" by Daisy Lion- 

 Goldschmidt of Paris [10]. Many of these pieces were obviously 

 made for religious and symbolic purposes, but over the centuries the 

 meaning of the symbols has been lost. 



In the late 18th century in China, especially under the patronage 

 of the Emperors K'ang-hsi and Ch'ien Lung, jade cutting was re- 

 vived and many fine artisans were brought into the service of the 

 Imperial Court. A new style was developed, entirely diflerent in 

 artistic conception from the style of earlier times, which resulted in 

 the production of large and flamboyantly worked vessels, plates, cups, 

 ornamental pieces, and small screens. Many of them were in the 

 shape and style of archaic bronzes. There are many fine examples of 

 this kind of jade in the Vetlesen collection [11] adjoinmg the gem 

 room in the Mineral Hall in the Museum of Natural History of the 

 Smithsonian Institution (pi. 3, fig. 1) ; also in the Bishop collection 

 of the Metropolitan Museum of Art and in the Dane collection in the 

 Fogg Museum of Art, Harvard University. Jades of this period, 

 because of their striking form and color, are often shown in catalogs 

 and picture books on Chinese art [12] . Recently from Russia has come 

 a splendidly illustrated book [9] showing unique pieces of Chinese 

 carved stone including much jade of the iTth and 18th centuries in 

 the famous Hermitage Museum in Leningrad. Many of the pieces 

 were collected by the former czars and nobles of Russia. 



For a long time it was not realized by either Europeans or Chmese 

 that the two kinds of minerals, jadeite and nephrite, are of different 

 composition until this was demonstrated by Damour in 1863. Wlien 

 pure, both varieties are white. Jadeite is an aggregate of small grains 

 and has, when polished, a sort of vitreous luster. Nephrite, on the 

 other hand, is built up of interlocking fibers, and has an oily luster ; 

 hence, white nephrite is appropriately called "mutton fat" jade. 

 Jadeite has a hardness of 6% on Mohs scale of 1 to 10; nephrite is 

 slightly less hard — 6I/2 — but has a peculiar toughness which gives it 

 greater resistance to lapidary tools and to breakage. Neither can be 

 scratched with the point of a pocketknife, whereas some other min- 

 erals used to imitate jade, such as serpentine, prophyllite, and steatite, 

 can be. The two minerals can easily be distinguished and told from 

 imitations by X-ray diffraction analysis. Nevertheless, both varieties 

 of mineral will continue to be called "jade." 



Rock crystal or transparent crystalline quartz (silicon dioxide, 

 SiOa) has been almost as important to art as jade. (PI. 3, fig. 2.) The 

 stonecutters of the Chinese Imperial Court work it much like jade 

 and converted long, stout crystals of clear quartz mto vases, jars, and 

 statuettes. The Philadelphia Museum of Art possesses some marvelous 



