Professor T. G. Bonney— Rocks from Kimherley. 449 



"No. 11, Soft Blue, East"; "No. 12, Hard Blue"; "No. 13, West- 

 side Blue"; "No. 14:, Soft Blue." All look rather decomposed, 

 No. 13 being, perhaps, in the best condition. The olivine grains are 

 serpentinized or still more decomposed. Brown mica is generally 

 present, but is not abundant; here and there a grain of iron-oxide 

 may be seen, and in one or two a garnet. No. 11 contains several 

 rounded fragments of a compact dull-green rock, with a slight zonal 

 structure near to and symmetrical with the exterior. The largest, 

 which is subangular in shape, measuring about 1" in length and |" 

 in breadth, has been examined microscopically, and will be described 

 later on. No. 12 contains a fair number of small fragments of shale, 

 which have a rather indurated aspect. The block also includes part 

 of a mass of calcite, with a dull-green border. The greatest length 

 of this mass, the exact nature of which I cannot determine, is 

 almost 1^". No. 13 also contains numerous fragments, very variable 

 in size. Of these a considerable pi'oportion, some angular, some 

 chip-like, represent a blackish shale, the largest specimen being about 

 1" in length. In No. 14 small chips of shale are rather numerous. 



A slice, was cut from (13), since this seemed the more promising 

 of the four specimens, but it could not be made sufficiently thin 

 to give any information of value. The larger olivine grains are 

 evidently much serpentinized. The rock fragments appear to be 

 a hard cai'bonaceous shale, but to these I shall return. 



One specimen, that belonging to Sir W. Crookes, comes from the 

 1,320-feet level, being marked " No. 22 level, north. Hard-blue." 

 This fragment is slightly pyramidal in shape, the base measuring 

 about 4|" X 3^", the greatest height being about 4". The s.g. is 

 2-783.^ The ground-mass is rather compact, in colour blackish- 

 grey, with a purplish tinge. Enclosures are numerous, varying 

 much in size and nature. Of the minerals, olivine is abundant in 

 grains of very variable size, which frequently seem to have escaped 

 serpentinization. Brown mica, garnets, and iron-oxide are also 

 visible, the first being the cominonest. Eock fragments are fairly 

 numerous, the most abundant being subangular in outline, dark dull- 

 green in colour, with a lighter border; they are rather serpentinous 

 in aspect, and have a hardness about 3. Some of the smaller are 

 distinctly redder in colour than the rest. Two or three fragments, 

 including the largest (about f " X f") are more of a grey-green in 

 colour (with a lighter margin), and have a more "speck-led" 

 aspect, but they do not materially differ in hardness. Time will be 

 saved by describing together the microscopic structure of this and 

 the next two specimens. These (in Sir J. B. Stone's collection), 

 from the 1,400-feet level, are distinguished on the labels as " 15, 

 East Blue " and " 16, West Blue." 



In (15), a fragment (? with a slight indication of parallel joint 

 planes) approximately 4" x 3" x IJ", the ground-mass resembles 

 that in the specimen last described. Grains and fragments are 

 scattered about it, but rather more sparsely than usual, and they 



^ The specific gravities were determined by a Walker's balance. In this and 

 several other matters I have to thank Miss C. A. Eaisin, B.Sc, for kind help. 



DECADE lY. VOL. IV. NO. X. 29 



