QUARTZ (TIGER-EYE) 495 



Like the Cape diamond, the minerals now under consideration are found in Griqualand 

 ^Vest, not at the same locaUties but in the neighbourhood of Griquatown, to the west of 

 Anuberley, the centime of the diamond mining area. In former times asbestiform crocidohte 

 and hmonite (brown iron-ore) were stated to occur in association with tiger-eye at Lakatoo 

 on the Orange River, and at Tulbagh, the material from the latter locality, according to 

 earlier accounts, being famed for its beauty. 



According to Professor E. Cohen, those occurrences of the minerals which are important 

 from an industi'ial point of view are situated in the mountain range north of the Orange 

 River which, a little \\est of Griquatown, extends first in a north to south, and then in a 

 north-east to south-west, direction. The continuation of this range on the other side of the 

 Orange River is formed by the Doom Bergen. On the large official map of Cape Colony 

 of 1876 this range is marked as the Asbestos mountains ; but in ordinary maps the name is 

 applied to a much shorter range, lying a little further to the east, and on these the former 

 range is marked as the Lange Bergen. 



Tiger-eye occurs at many jilaces in this range, among others in the neighbourhood of 

 Griquatown. The plates are embedded in a finely grained quartz-rock of a reddish-brown, 

 coffee-brown, or ochre-yellow colour. The mountains, which do not stand very high above 

 the plateau, are composed mainly of this rock, which is often very thinly bedded, and may 

 be best described as a jasper-schist. The mineral is quarried here and sent in large 

 quantities to Europe, especially to Oberstein on the Nahe and the neighbouring town of 

 Idar, to be cut. 



Tiger-eye was once a great rarity in Europe ; not more than a quarter of a century 

 ago it cost upwards of 25s. per carat. Now, owing to the underselling of two rival traders, 

 the stone has been placed on the market in such large quantities that the price has fallen 

 to little more than Is. a pound. 



All the tiger-eye and hawk's-eye which comes into the market is obtained from the 

 Asbestos mountains, but the mineral is not by any meaiis confined wholly to this district, 

 and appears to have a wide distribution in South Africa. The traveller Mauch has found 

 it, for example, much further to the east, on the upper Marico, a tributary of the Orange 

 River. Outside South Africa, however, neither tiger-eye nor hack's eye has hitherto been 

 found. 



While these stones were rare and costly they were cut with a flat or convex polished 

 surface, and were used as gems for rings, brooches, and such like. Later on, when the price 

 had fallen considerably, they began to be used for the manufacture of small articles of 

 utility or ornament, such as the handles of umbrellas, and at the present time figures in 

 bas relief, and intaglios are sometimes cut from fine specimens. Tiger-eye, indeed, has now 

 a considerable application in the manufacture of ornamental and semi- ornamental objects, 

 but hawk's eye, being less abundant, is much less extensively used. In cutting either of 

 these stones care must be taken that the cut and polished surface is as nearly as possible 

 parallel to the fibres ; a slight deviation from this rule has a very prejudicial effect on the 

 appearance of the stone. 



It has been mentioned above that tiger-eye, after treatment with hydrochloric acid, 

 assumes an appearance similar to that of grey cafs-eye ; this is due to the fact that the 

 hydrated iron oxide is extracted, and the fibrous silica left behind. The names tiger-eye 

 and hawk's-eye have reference to the fact that these stones differ from cafs-eye in colour, 

 bub when cut en cabocJion possess exactly the same chatoyant appearance, 



