THE FELSPAR GROUP (LABRADORITE) 4f53 



play of coloui- is less striking. To get the best possible effect the direct rays of the sun or 

 of a powerful artificial light must fall upon the second cleavage surface at a certain definite 

 angle, and the eye of the observer placed in a suitable position to receive the reflected rays. 

 The stone is cut, not with facets, which destroy its effect, but either perfectly plane, or with 

 a very slightly convex surface, which must be parallel to the reflecting surface. If the cut 

 and polished surface deviates far from this position no play of colour will be seen. It is 

 evident, moreover, from what has been said, that the play of colour is only exhibited by a 

 cut-stone when in a certain position relative to the incident light and the eye of the 

 observer, and that it suddenly disappears with the smallest deviation from this position. 



This sudden disappearance and reappearance of brilliant chatoyant colours is specially 

 characteristic of labradorite, and constitutes one of its most striking features. On this 

 account the stone is known to jewellers also as changeant ; and the play of colour as change 

 of colour or labradorescence. 



The sheen of labradorite is metallic, and at the same time brilliantly and intensely 

 coloured. There is no art by which a reproduction or an imitation of it in any way 

 comparable to the original may be produced. The colours recall those of iridescent objects 

 and of precious opal, but in the latter case each surface shows a number of sharply defined 

 and differently coloured patches, while in labradorite there are large areas presenting one 

 uniform colour. The sheen of this stone may perhaps be best likened to certain other 

 natural objects, such as the wings of tropical butterflies, which display the same kind of 

 metallic colours, though even more lustrous and brilliant. As examples may be cited 

 Morpho cypris and Morpho achilles of a beautiful blue colour, and Apatura seraphina which 

 is green in colour, all being from South America. 



The range of colour exhibited by labradorite is wonderfully extensive. There are 

 blues of all tints from pure smalt-blue to violet ; greens ranging from the purest emerald 

 tint to blue and yellow ; the most brilliant golden yellow, a bright lemon-yellow, a deep 

 and intense orange, which shades oft' gradually in a strong copper-red or a warm tombac- 

 brown. In some stones the metallic sheen varies in colour as the stone is turned about ; 

 thus in one position it appears of a green colour and in another yellow ; such a change is 

 not, however, frequently met with. In Plate XVI., Fig. 2, an attempt has been made to 

 reproduce the magnificent colour effects of labradorite. 



I^abradorite of different colours differs also in the frequency with which it is found ; 

 thus blue and green are most commonly, and yellow and red most rarely, seen. It is not 

 unusual for the reflecting surface of a specimen to show a sheen of one uniform colom* over 

 the whole area of that surface, as in labradorite with a blue sheen from Brisbane in 

 Australia, the variety represented in Plate XVI., Fig. 2. More commonly, however, the 

 same surface displays elongated streaks and irregular patches, which differ in colour and 

 in intensity of colour, and are not very sharply defined. An interesting specimen of 

 labradorite, not from Labrador but from Russia, has been described by the Parisian 

 jeweller Caire. According to his description it displays a perfectly recognisable image of 

 Louis XVI. : the head of the finest azure-blue colour stands out from a golden-green 

 background, and is surmounted by a beautiful garnet-red crown with a border of rainbow 

 colours, and a small, silvery, shining plume. The sum of a quarter of a million francs 

 (.£10,000) was demanded in 1799 by the owner of this remarkable object. 



The metallic sheen of labradorite is not always displayed uninterruptedly over the 

 whole reflecting surface, for there are often areas which show nothing but the dull body- 

 colour of the stone. These areas often take the form of long, narrow strips with straight, 

 parallel margins, and these may alternate with similar strips showing the most beautiful 



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