Oil Boulder* ii<! Jtock Specimens from Gfriquakmd West. 475 



" Additional Xutes on Boulders and other I Jock Specimens from 

 the Xewlands Diamond Mines, (Iriijualaml West." Hy T. G. 

 BOXX-EY, D.Sc., LL.1)., FR.S., Professor of Geology, University 

 College, London. Received Xo\>>ml>er 21, Road December 

 13, 1900. 



The invasion of Griqualand at the beginning of the war with the 

 Transvaal and Free State, put a stop, for a time, to working the New- 

 lands Diamond Mines, some interesting specimens from which were 

 brought to the notice of the Royal Society, on June 1st, in last year.* 

 But shortly before the hurried departure of the employes, another 

 small collection had been despatched to Mr. G. Trubenhach, the 

 Managing Director in London, which he showed to me, early in the 

 present year, most kindly placing the new specimens at my disposal for 

 study. Some represented boulders, some the diamantiferous breccia, 

 popularly called "' blue ground/' in which these occur ; some the 

 " country rock." The first,- though (so far as can be seen) without 

 diamonds, include at least four additional species of rock ; the second 

 throw a little more light on the past history of the matrix. Moreover, 

 they come from a new set of workings to the north-east of the former, 

 where a shaft has been sunk, and galleries driven at a depth of about 

 46o feet. Apparently two " pipes " are connected by a narrow fissure 

 filled with breccia. t So I have ventured to communicate the result of 

 my investigations to the Royal Society, including with them a short 

 note on a residue obtained- by Sir William Crookes, F.R.S., after dis- 

 solving away almost the whole of a small fragment of the remarkable 

 diamantiferous eclogite which was described in June, 1899. 



(1.) The BouUtr*. 



('?.) Of these one is rudely semi-oval in outline, measuring aVmt 

 U inches in greatest length and breadth, and H inch thick, being 

 probably a piece broken from an ellipsoidal pebble. The rock is liolo- 

 crystalline, composed chiefly of a pyroxene resembling bastite and of 

 olivine, converted on the older-looking surfaces into a pale-screen 

 serpentinous material. Examination of a thin slice shows the rock to 

 consist mainly of olivine, which exhibits incipient serpentinisation 

 along cracks in the usual manner, and of a very pale brownish-green 

 bastite, with one close cleavage : and possibly one or two small grains 

 of a monoclinic pyroxene ; spinel, and even original iron oxide, being 

 apparently absent. Specific gravity, 3*074. 



* ' Roy. Soc. Proc.,' vol. 65, p. 223. 



t The precise depth at which the specimens were obtained cannot be given, as 

 Ihe labels became illegible in the hurried transit. 



