CHRYSOBERYL: OCCURRENCE 303 



The sudden popularity of chrvsoberyl-cat's-eye caused by the use of this stone in the ring 

 given by the Duke of Connaught to \i\s Jiancee, has been already mentioned. It resulted in 

 a great rise in its price, the stone being now about equal in value to a " balas-ruby." 



The finest and largest chrysoberyl-cafs-eye known was included in the famous Hope 

 collection, and is figured by B. Hertz in his Catalogue of the Collection of Pearls and 

 Precious Stones formed hy Henri/ Philip Hope, published in ] 839. This stone is nearly 

 hemispherical in shape, the diameter in the direction of the splendid chatoyant band 

 measuring 2 inches and slightly exceeding the other diameter. It is dark in colour and 

 the band of light which crosses it is not absolutely perfect, being nicked slightly in the 

 middle. Among other fine stones now known is a magnificent jewel, sold in America, 

 measuring 23 millimetres (nearly 1 inch) in length and breadth and 17 millimetres in 

 thickness, and weighing 80| carats. It is yellowish-brown in colour, and the band of light 

 which crosses it is wonderfully sharp, narrow, and straight for so large a stone. 



The transparent varieties of chrysoberyl, especially those of a fine golden-yellow colour,, 

 are cut usually as brilliants, the step-cut and mixed-cut, however, being sometimes employed. 

 Unless the colour is very intense this gem is seldom mounted a jour, more usually a closed 

 setting with a foil of burnished gold to deepen the colour of the stone is employed. The 

 opaque varieties, or cafs-eye, are of course cut en cahochon. Such stones are usually cut with 

 an oval outline so that the band of light coincides in direction with the major axis of the 

 oval. 



The most important locality for chrysoberyl is Brazil, the district of Minas Novas, in 

 the north of the State of Minas Geraes, being specially rich. It is found associated with 

 rock-crystal, amethyst, red quartz, green tourmaline, yellowish-red spinel (so-called " vinegar- 

 spinel "), garnet, euclase, and especially with white and blue (but not yellow) topaz. 



Chrysoberyl is one of the finest coloured precious stones found in Brazil. It is known 

 to Brazilians and in the trade generally as " chrysolite." It exhibits considerable variety of 

 colour within certain limits, greyish-white, pale ochre-yellow, citron-yellow, olive-green, 

 gi-ass-gi-een, and pale green being shades of colour ordinarily seen, while pure wine-yellow,, 

 greyish-yellow, and colourless stones sometimes occur. The last-named variety closely 

 approaches the diamond in brilliancy and transparency. Stones of perfect transparency are 

 rare, the chatoyancy of cat's-eye being, as a rule, more or less prominent even in the 

 transparent varieties. Chrysoberyl, especially the variety of a pure green colour, is very 

 highly esteemed in Brazil, and consequently commands a high price, being more expensive in 

 that country than in Europe. 



The mineral occurs as pebbles, not, as a rule, larger than a bean. A block of supposed 

 chrysoberyl weighing 16 pounds is reported to have been once found, but it is more likely to 

 have been aquamarine (beryl). In spite of the fact that the pebbles are rounded and 

 water-worn, the broad, striated face, which is shown in Fig. 61, and parallel to which the 

 crystals are usually tabular, is often easily recognisable. They are found in an auriferous 

 mud or clay derived from the weathering of granite and gneiss, rocks which are always to 

 be found in the vicinity of deposits containing chrysoberyl. It would appear from this fact 

 that chrysoberyl was originally formed in such rocks, but so far the mineral has been met 

 with only in secondary deposits. Among the principal localities for the mineral may be 

 mentioned the upper course of the Piauhy, and the neighbourhood about the source of the 

 Calhao stream. These deposits, however, are less rich than in former times, and it is said 

 that at the present day material suitable only for the pivot-supports of watches is found 

 there. Chrysoberyl also occurs associated with diamond in small amount in Minas 

 Geraes. 



