Rocks from the Kimherley Diamond-Mines. 413 



by Prof, T. Kupert Jones and, by kind permission of Prof. Bonney, 

 was submitted to him for examination, in packets marked I, — VIII. 

 and X. Specimen No. IX. was sent many years ago, as a trap- 

 rock with garnets from the Vaal Eiver, by Mr. Kobert Crofts 

 Jones.— T. R. J.] 



For the most part the specimens were too small to permit of 

 slices being made ; the results therefore were in such cases obtained 

 by examining the powder got by crushing the fragments. 



I. a. The green mineral is Enstatite, and is associated with a 

 colourless transparent mineral, appearing cracked and fractured, 

 which seems to be probably Topaz. 



p. A clear bright-green crystal of Enstatite. 



7. The green mineral is a Pyroxene, and is intercrystallized with 

 red Garnets. 



h. A slide was prepared of this specimen, which showed that it 

 consisted of Garnets enclosed in a green Pyroxene, probably Ompha- 

 cite, with small rifts or tubuli traversing the crystal transverse to 

 the prism-zone. A colourless transparent mineral is associated with 

 the Pyroxene ; it has straight, or nearly straight, extinction, and 

 might be Zoisite or possibly Kyanite. 



II. a. A transparent, pale, resin -coloured specimen of Topaz. 



yS. A bright green Pyroxene, with a yellowish or greenish-grey 

 mineral, which has one good cleavage and straight extinction, and 

 may be Zoisite. Very dull purplish Garnets are included, and flakes 

 of brown Mica. 



7. A Pyroxene of rather foliated habit, having a clear, deep, rich 

 green colour and a sub-metallic lustre, apparently like the Omphacite 

 described by von Drasche. To this is attached a white fibrous 

 mineral evidently a carbonate, probably Calcite. 



8. A pale sea-green mineral with silky or pearly lustre, which 

 shows well-marked cleavages, breaks into rhomboidal forms, and 

 appears to be a variety of Diallage. 



III. Many specimens of Iron-pyrites; also others of a rock 

 composed of Pyroxene, Garnet, and (?) Zoisite. 



IV. a. Matrix seems to consist of minutely granular Serpentine 

 and Olivine with some brown Mica — a ground-mass apparently 

 similar to that in the slide cut from specimen VI. Green crystals of 

 Augite are enclosed. 



/3. Garnets enclosed in a clear greenish mineral, very pale in tint 

 when seen in thin flakes under the microscope, and somewhat 

 foliated ; it is probably a pyroxene of the nature of Omphacite. 



7. Three specimens of Garnet-pyroxene-mica-rock, as described, II. /S. 



L Three specimens of Garnet-pyroxene- {?)zoisite-rock, as pre- 

 viously described. III. 



V. Specimens of Ilmenite (called "carbon " by the miners). 



VI. A slide prepared from this rock shows a ground-mass, the 

 constituents of which are difficult to distinguish ; it appears to be an 

 irregular mixture of brown Mica, brownish-green Serpentine, and 

 a dirty-looking mineral, which is seen with polarized light as an 

 aggregate of fine granules, and in parts seems to be associated with 



