THE SOUTH-AFRICAN DIAMOND-MINES. 473 



In quality the Yaal River stones are rated highest, in the degree 

 that while in the three years ending with August, 1885, the weight of 

 those sent away from that district was only about T |-^, that of the en- 

 tire exports their declared value was as much as ^V of the total value 

 exported. Of the four Kimberley and Beaconsfield mines, Dutoits- 

 pan produces the finest stones, ninety per cent being perfect. Bult- 

 fontein comes next, with its beautiful white stones, weighing from a 

 quarter of a carat to two carats. De Beer's comes next, and Kimber- 

 ley last. In absolute value of production, the order is, Dutoitspan, 

 De Beer's, Kimberley, Bultfontein. The largest diamond ever found 

 in Griqualand West was an irregular octahedron from Dutoitspan, 

 slightly spotted, and of yellow color, which weighed 404 carats, or 

 nearly three ounces. The only larger stone than this known to have 

 ever been found was a very imperfect one, discovered near Jagers- 

 fontein, which weighed about 500 carats. Another diamond, of 352 

 carats, has been found at Dutoitspan. The largest stone ever found 

 at Bultfontein weighed a little more than 150 carats. The Bultfontein 

 diamonds, while superior in color to all others except those of Jagers- 

 fontein, are of smaller average size than those of the other three 

 mines. 



All the diamonds coming from the various South-African mines 

 are said to have a distinct personality, by means of which experts can 

 at once recognize stones from either of the four mines, and tell from 

 which it came, and can again distinguish those of the Kimberley and 

 Beaconsfield mines from those of the river-diggings, and their testi- 

 mony on this point is accepted by the courts. 



All the theories by which the attempt is made to account for these 

 mines recognize them as of volcanic origin. Their form suggests at 

 once the crater of an extinct volcano, or the tube of a geyser. When 

 the attempted explanation goes beyond this, the range of diverging 

 opinions is quite wide. Of these various views, we will refer only to 

 the observation of Sir Henry Roscoe, that the most noteworthy feat- 

 ure of the diamond-bearing rocks of Kimberley is the discovery in the 

 diamond-earth of a volatile crystalline hydrocarbon, soluble in ether, 

 which seems to confirm the hypothesis that the carboniferous shales, 

 which are penetrated by the diamond-bearing pipes, have been the 

 source of the carbon now found in the crystalline state in this gem. 

 The physical structure of the ash, or incombustible portion of the stone, 

 is of a very singular character, and has hitherto not been examined. 

 A careful study of it may possibly throw light on the important ques- 

 tion of the mode of formation of the diamond. 



