1899] THE SOUTH AFRICAN DIAMOND 177 



with, or indenting, or actually embedded in a fairly large, somewhat 

 irregularly shaped pyrope. The one specimen came from Kimberley ; 

 the other from the Newlands Mines, West Griqualand, and it was found 

 by Mr. G. Trubenbach, the managing director in England of the 

 Company, during a visit to South Africa. 



In these mines, as in the I)e Beers Mine, 1 rounded boulders occa- 

 sionally occur in the diamond-bearing rock — the blue ground (soft or 

 hard, as the case may be). Mr. Trubenbach brought some of these 

 from the former locality to England, and a small diamond was then 

 observed to be exposed on the surface of one of them ; the boulder was 

 broken and others were disclosed. One fragment was sent to Sir W. 

 Crookes, to obtain the benefit of his opiuion, and he showed it to me. 

 Though I saw it by artificial light, I felt certain that the rock was not 

 any variety of the breccia, but a true eclogite, and expressed that 

 opinion. He most kindly asked me to examine the rock, and obtained 

 from the directors permission for me to cut off as much as I thought 

 necessary for a satisfactory investigation. I am deeply indebted to him 

 for this kindness, and to Mr. Trubenbach for aiding me with other 

 specimens from the mines and responding so willingly to my inquiries. 

 An account of my examination of the whole series was communicated 

 to the Eoyal Society on 1st June,'" 2 and the following are the principal 

 results : — 



The boulders of eclogite were six in number, but all prior to 

 fracture had been well rounded. Stones of similar shapes might 

 readily be found in the bed of an Alpine torrent after a course of 

 several miles — in other words, I am sure they are water-worn. 

 Three are of one species of eclogite, and three of another ; two of the 

 former beino; known to contain diamonds. That in which this mineral 

 was first discovered is apparently from a quarter to a third of an ellip- 

 soidal boulder, its axial measurements being roughly 4 in. x 3 in. x '2 in. 

 The other specimen, probably about a quarter of the original, measured 

 in the same way about 5|- in. x 5 in. x 3^ in. The outer surface of the 

 former specimen is smooth ; the pyropes 3 barely, if at all, projecting. 

 So it has been in the other, but the surface now is slightly corroded. 

 Near the exterior the pyropes, as is often the case, are covered by a 

 dark outer film, thicker than the thumb-nail, but this is hardly per- 

 ceptible near the centre. 



The first-named specimen is comparatively rich in diamonds. 

 Two are visible on the smooth outer surface, a third on one of the 

 fractured faces, and seven on the other, but two of these (partially 



1 The occurrence of boulders in the blue ground of this mine (among them granite and 

 eclogite) was mentioned so long ago as 1S93 by A. W. Stelzner, Sitzungber. u. Abkandl. 

 der Isis, Dresden, 1893, p. 71. 



2 Proc. Roy. Soc. London, 1899. 



3 I follow previous writers in applying that name to the red garnet of this rock and the 

 washings. Its accuracy is confirmed by the fact that magnesia-mica is so abundant in the 

 kelyphite rim. 



12 XAT. SC. VOL. XV. NO. 91. 



