JADEITE— CHLOROMELANITE 467 



sharply defined spots of a fine emerald-green colour. These latter are due to the presence 

 of a small amount of chromium distributed through the stone in this irregular manner. 

 The colour of the varieties ^^hich show a uniform shade of pale green is due to the presence 

 of a small amount of iron. Chloromelanite, since it always contains a considerable amount 

 of iron, is never colourless or pale in shade, but always dark green or almost black. 



Having considered the features in which jadeite and chloromelanite are in agreement 

 with nephrite, we must now pass to the consideration of their distinguishing characters. 



The most important of these is the specific gravity. Jadeite is denser than nephrite, 

 the specific gravity of the former varying between 3"30 and 3'35, while that of the 

 chloromelanite variety, owing to the larger amount of iron present, reaches 3"4. Although 

 in the majority of cases this is a valuable aid in discriminating between these minerals, it 

 does occasionally happen that a specimen of jadeite, owing to the presence of inclusions of 

 foreign matter, has a specific gravity as low as that of nephrite, and cannot be distinguished 

 in this way. It is generally safe to assume, however, that a stone with a specific gravity of 

 3"3 is not nephrite. Thei-e is a slight difference between the hardness of the minerals, that 

 of jadeite (H = 6| — 7) being rather higher than that of nephrite. 



Another important difference between these minerals is the ease with which they can 

 be fused. While nephrite fuses only with great difficulty, jadeite and chloromelanite are 

 very easily fusible ; indeed, splinters of typical chloromelanite or jadeite will fuse to a 

 transparent, blebby glass even in the flame of a spirit-lamp without using a blowpipe at 

 all. This is not invariably the case, however, for some specimens of jadeite and of 

 chloromelanite are rather difficultly fusible, though never as much so as nephrite. In 

 performing these blowpipe experiments it will be noticed that jadeite and chloromelanite, 

 since they contain sodium, colour the flame an intense yellow, while nephrite does not 

 do so. 



Setting aside chemical analysis, the surest means \\hereby these minerals may be 

 distinguished is by the examination of thin sections under the microscope. It is always 

 possible to find some fibres which show the cleavage or optical features characteristic of 

 augite or of hornblende, the mineral in the former case being jadeite or chloromelanite and 

 in the latter nephrite. Although only a very small splinter of matei'ial is necessary for the 

 investigation of the fusibility, chemical composition, and microscopic structure of any given 

 stone, it may be inadmissible to remove even this from a worked object, and in such cases 

 the only test applicable is the determination of the specific gravity. 



Objects worked in jadeite of prehistoric age have been found frequently in Europe, 

 Asia, America, and Africa, but the localities from whence the rougli material was obtained 

 are in most cases practically unknown. The only locality which has been thoroughly examined 

 from a scientific point of view, and where large masses of jadeite are known to occur iii situ, 

 is in northern Burma. The material from this deposit, like nephrite from its Asiatic localities, 

 is distributed over the whole of the Orient, where it is highly esteemed and used for the 

 same purposes as nephrite ; from which, indeed, it is often not distinguished, being included 

 with this stone under the term "yu." Like nephrite, jadeite is not much esteemed in 

 Europe, and is seldom applied to purposes of oi'nament. 



Objects made of chloromelanite accompany jadeite articles in France, Switzerland, 

 Mexico, and Colombia, while a large axe of the same material has been found at Humboldt 

 Bay in New Guinea. Chloromelanite in the rough condition has never yet been met with ; 

 the articles which are found fashioned out of it all date back to remote antiquity, and are 

 rarer than either nephrite or jadeite objects. Its existence as a distinct mineral was first 

 recognised in an axe-head found in Erancc. 



